Triggered target wake time operation

ABSTRACT

A method, an apparatus, and a computer-readable medium for wireless communication are provided. In an aspect, an apparatus may be configured to determine whether to switch to an active mode, a power save mode, or a TWT power save mode. During the TWT power save mode, the apparatus may enter an awake state during TWT service periods and may enter a doze state outside of the TWT service periods. The apparatus may transmit a message to a second wireless device based on the determination.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a divisional application of U.S. Non-Provisionalapplication Ser. No. 15/008,409, entitled “TRIGGERED TARGET WAKE TIMEOPERATION” and filed on Jan. 27, 2016, which claims the benefit of U.S.Provisional Application Ser. No. 62/109,024, entitled “TRIGGERED TARGETWAKE TIME OPERATION” and filed on Jan. 28, 2015, U.S. ProvisionalApplication Ser. No. 62/126,403, entitled “TRIGGERED TARGET WAKE TIMEOPERATION” and filed on Feb. 27, 2015, U.S. Provisional Application Ser.No. 62/244,682, entitled “TRIGGERED TARGET WAKE TIME OPERATION” andfiled on Oct. 21, 2015, U.S. Provisional Application Ser. No.62/245,941, entitled “TRIGGERED TARGET WAKE TIME OPERATION” and filed onOct. 23, 2015, U.S. Provisional Application Ser. No. 62/260,155,entitled “TRIGGERED TARGET WAKE TIME OPERATION” and filed on Nov. 25,2015, and U.S. Provisional Application Ser. No. 62/278,366, entitled“TRIGGERED TARGET WAKE TIME OPERATION” and filed on Jan. 13, 2016. Eachapplication identified above is incorporated by reference herein in itsentirety.

BACKGROUND Field

The present disclosure relates generally to communication systems, andmore particularly, to triggered target wake time operation.

Background

In many telecommunication systems, communications networks are used toexchange messages among several interacting spatially-separated devices.Networks may be classified according to geographic scope, which couldbe, for example, a metropolitan area, a local area, or a personal area.Such networks would be designated respectively as a wide area network(WAN), metropolitan area network (MAN), local area network (LAN),wireless local area network (WLAN), or personal area network (PAN).Networks also differ according to the switching/routing technique usedto interconnect the various network nodes and devices (e.g., circuitswitching vs. packet switching), the type of physical media employed fortransmission (e.g., wired vs. wireless), and the set of communicationprotocols used (e.g., Internet protocol suite, Synchronous OpticalNetworking (SONET), Ethernet, etc.).

Wireless networks are often preferred when the network elements aremobile and thus have dynamic connectivity needs, or if the networkarchitecture is formed in an ad hoc, rather than fixed, topology.Wireless networks employ intangible physical media in an unguidedpropagation mode using electromagnetic waves in the radio, microwave,infra-red, optical, etc., frequency bands. Wireless networksadvantageously facilitate user mobility and rapid field deployment whencompared to fixed wired networks.

SUMMARY

The systems, methods, computer-readable medium, and devices of theinvention each have several aspects, no single one of which is solelyresponsible for the invention's desirable attributes. Without limitingthe scope of this invention as expressed by the claims which follow,some features will now be discussed briefly. After considering thisdiscussion, and particularly after reading the section entitled“Detailed Description,” one will understand how the features of thisinvention provide advantages for devices in a wireless network.

One aspect of this disclosure provides an apparatus (e.g., a station oran access point) for wireless communication. The apparatus may beconfigured to transmit a first message that includes a first triggerfield to a second wireless device. The first trigger field may indicatewhether the first message includes a request for a trigger message (orframe) to be sent by the second wireless device at a start of one ormore target wake times (TWTs) of one or more TWT service periods. In anaspect, the TWT may be referred to as the target trigger time (TTT), orany other time reference. The apparatus may be configured to receive asecond message from the second wireless device. The second message mayinclude a second trigger field based on the first message, and thesecond trigger field may indicate whether the second wireless devicewill transmit the trigger message at the start of the TWT serviceperiod. In certain embodiments, the second message may be sent to thefirst wireless device without receiving a first message. In certainembodiments, the message may be multicast or broadcast.

Another aspect of this disclosure provides an apparatus (e.g., a stationor an access point) for wireless communication. The apparatus may beconfigured to receive, from a second wireless device, a first messagethat includes a first trigger field. The first trigger field mayindicate whether the first message includes a request for a triggermessage to be sent by the first wireless device at a start of a TWTservice period. The apparatus may be configured to determine a TWTschedule based on the received first message. The apparatus may beconfigured to transmit a second message to the second wireless device.The second message may include the TWT schedule and a second triggerfield based on the determined TWT schedule. The second trigger field mayindicate whether the apparatus will transmit the trigger message at thestart of the TWT service period.

Another aspect of this disclosure provides an apparatus (e.g., a stationor an access point). The apparatus may be configured to determine a TWTschedule. The apparatus may be configured to broadcast a message thatincludes the TWT schedule to a number of wireless devices. The messagemay include a broadcast indicator that indicates the TWT schedule is abroadcast TWT schedule.

Another aspect of this disclosure provides an apparatus (e.g., a stationor an access point). The apparatus may be configured to receive from asecond wireless device a message that includes a TWT schedule. Themessage may include a broadcast indicator that indicates the TWTschedule is a broadcast TWT schedule. The apparatus may be configured todetermine one or more TWTs for the first wireless device based on theTWT schedule.

Another aspect of this disclosure provides an apparatus (e.g., a stationor an access point). The apparatus may be configured to determinewhether to switch to an active mode, a power save mode, or a TWT powersave mode. During the TWT power save mode, the apparatus may enter anawake state during TWT service periods and may enter a doze stateoutside of the TWT service periods. The apparatus may be configured totransmit a message to a second wireless device based on thedetermination of whether to switch modes.

Another aspect of this disclosure provides an apparatus (e.g., a stationor an access point). The apparatus may be configured to receive amessage from a second wireless device that indicates an intention of thesecond wireless device to switch to an operating mode. The operatingmode may be one of an active mode, a power save mode, or a TWT powersave mode. During the TWT power save mode, the second wireless devicemay enter an awake state during TWT service periods and may enter a dozestate outside of the TWT service periods. The apparatus may beconfigured to store the operating mode associated with the secondwireless device. The apparatus may be configured to transmit to thesecond wireless device an acknowledgment of the operating mode switch.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an example wireless communication system in which aspectsof the present disclosure may be employed.

FIG. 2 is an exemplary diagram of a target wake time element forsupporting target wake time and trigger frame scheduling.

FIG. 3 is an exemplary diagram of a wireless network implementingsolicit TWT scheduling and an exemplary timing flow diagram for TWToperation.

FIG. 4 is a flowchart of an example method of requesting TWT scheduling.

FIG. 5 is a flowchart of an example method of responding to a requestfor, or transmitting information related to, TWT scheduling.

FIG. 6 is an exemplary diagram of a wireless network implementingbroadcast TWT scheduling and an exemplary timing flow diagram for TWToperation.

FIG. 7 is a flowchart of an example method of broadcast TWT scheduling.

FIG. 8 is a flowchart of an example method of communicating based onbroadcast TWT scheduling.

FIG. 9 is an exemplary diagram of a wireless network supporting powersave modes for TWT scheduling and an exemplary timing flow diagram forTWT operation.

FIG. 10 is a flowchart of an example method of switching to or from aTWT power save mode.

FIG. 11 is a flowchart of an example method of signaling for switchingto a TWT power save mode.

FIG. 12 is an exemplary diagram of a request type field within a TWTelement for broadcast TWT.

FIG. 13 illustrates a method of broadcasting TWTs for multiple TWTs.

FIG. 14 illustrates a method of employing a cascaded field in a triggerframe within a TWT service period.

FIG. 15 is an exemplary diagram of a TWT group assignment field within aTWT element for a broadcast TWT for multiple STAs.

FIG. 16 illustrates an exemplary diagram of a second TWT element format.

FIG. 17 shows an example functional block diagram of a wireless devicethat may perform TWT scheduling within the wireless communication systemof FIG. 1.

FIG. 18 is a functional block diagram of an example wirelesscommunication device that performs TWT scheduling.

DETAILED DESCRIPTION

Various aspects of the novel systems, apparatuses, computer-readablemedium, and methods are described more fully hereinafter with referenceto the accompanying drawings. This disclosure may, however, be embodiedin many different forms and should not be construed as limited to anyspecific structure or function presented throughout this disclosure.Rather, these aspects are provided so that this disclosure will bethorough and complete, and will fully convey the scope of the disclosureto those skilled in the art. Based on the teachings herein one skilledin the art should appreciate that the scope of the disclosure isintended to cover any aspect of the novel systems, apparatuses, computerprogram products, and methods disclosed herein, whether implementedindependently of, or combined with, any other aspect of the invention.For example, an apparatus may be implemented or a method may bepracticed using any number of the aspects set forth herein. In addition,the scope of the invention is intended to cover such an apparatus ormethod which is practiced using other structure, functionality, orstructure and functionality in addition to or other than the variousaspects of the invention set forth herein. It should be understood thatany aspect disclosed herein may be embodied by one or more elements of aclaim.

Although particular aspects are described herein, many variations andpermutations of these aspects fall within the scope of the disclosure.Although some benefits and advantages of the preferred aspects arementioned, the scope of the disclosure is not intended to be limited toparticular benefits, uses, or objectives. Rather, aspects of thedisclosure are intended to be broadly applicable to different wirelesstechnologies, system configurations, networks, and transmissionprotocols, some of which are illustrated by way of example in thefigures and in the following description of the preferred aspects. Thedetailed description and drawings are merely illustrative of thedisclosure rather than limiting, the scope of the disclosure beingdefined by the appended claims and equivalents thereof.

Popular wireless network technologies may include various types ofWLANs. A WLAN may be used to interconnect nearby devices together,employing widely used networking protocols. The various aspectsdescribed herein may apply to any communication standard, such as awireless protocol.

In some aspects, wireless signals may be transmitted according to an802.11 protocol using orthogonal frequency-division multiplexing (OFDM),direct-sequence spread spectrum (DSSS) communications, a combination ofOFDM and DSSS communications, or other schemes. Implementations of the802.11 protocol may be used for sensors, metering, and smart gridnetworks. Advantageously, aspects of certain devices implementing the802.11 protocol may consume less power than devices implementing otherwireless protocols, and/or may be used to transmit wireless signalsacross a relatively long range, for example about one kilometer orlonger.

In some implementations, a WLAN includes various devices which are thecomponents that access the wireless network. For example, there may betwo types of devices: access points (APs) and clients (also referred toas stations or “STAs”). In general, an AP may serve as a hub or basestation for the WLAN and a STA serves as a user of the WLAN. Forexample, a STA may be a laptop computer, a personal digital assistant(PDA), a mobile phone, etc. In an example, a STA connects to an AP via aWi-Fi (e.g., IEEE 802.11 protocol) compliant wireless link to obtaingeneral connectivity to the Internet or to other wide area networks. Insome implementations, a STA may also be used as an AP.

An access point may also comprise, be implemented as, or known as aNodeB, Radio Network Controller (RNC), eNodeB, Base Station Controller(BSC), Base Transceiver Station (BTS), Base Station (BS), TransceiverFunction (TF), Radio Router, Radio Transceiver, connection point, orsome other terminology.

A station may also comprise, be implemented as, or known as an accessterminal (AT), a subscriber station, a subscriber unit, a mobilestation, a remote station, a remote terminal, a user terminal, a useragent, a user device, a user equipment, or some other terminology. Insome implementations, the station may comprise a cellular telephone, acordless telephone, a Session Initiation Protocol (SIP) phone, awireless local loop (WLL) station, a personal digital assistant (PDA), ahandheld device having wireless connection capability, or some othersuitable processing device connected to a wireless modem. Accordingly,one or more aspects taught herein may be incorporated into a phone(e.g., a cellular phone or smartphone), a computer (e.g., a laptop), aportable communication device, a headset, a portable computing device(e.g., a personal data assistant), an entertainment device (e.g., amusic or video device, or a satellite radio), a gaming device or system,a global positioning system device, or any other suitable device that isconfigured to communicate via a wireless medium.

The term “associate,” or “association,” or any variant thereof should begiven the broadest meaning possible within the context of the presentdisclosure. By way of example, when a first apparatus associates with asecond apparatus, it should be understood that the two apparatuses maybe directly associated or intermediate apparatuses may be present. Forpurposes of brevity, the process for establishing an association betweentwo apparatuses will be described using a handshake protocol thatrequires an “association request” by one of the apparatus followed by an“association response” by the other apparatus. It will be understood bythose skilled in the art that the handshake protocol may require othersignaling, such as by way of example, signaling to provideauthentication.

Any reference to an element herein using a designation such as “first,”“second,” and so forth does not generally limit the quantity or order ofthose elements. Rather, these designations are used herein as aconvenient method of distinguishing between two or more elements orinstances of an element. Thus, a reference to first and second elementsdoes not mean that only two elements can be employed, or that the firstelement must precede the second element. In addition, a phrase referringto “at least one of” a list of items refers to any combination of thoseitems, including single members. As an example, “at least one of: A, B,or C” is intended to cover: A, or B, or C, or any combination thereof(e.g., A-B, A-C, B-C, and A-B-C).

As discussed above, certain devices described herein may implement the802.11 standard, for example. Such devices, whether used as a STA or APor other device, may be used for smart metering or in a smart gridnetwork. Such devices may provide sensor applications or be used in homeautomation. The devices may instead or in addition be used in ahealthcare context, for example for personal healthcare. They may alsobe used for surveillance, to enable extended-range Internet connectivity(e.g. for use with hotspots), or to implement machine-to-machinecommunications.

FIG. 1 shows an example wireless communication system 100 in whichaspects of the present disclosure may be employed. The wirelesscommunication system 100 may operate pursuant to a wireless standard,for example the 802.11 standard. The wireless communication system 100may include an AP 104, which communicates with STAs (e.g., STAs 112,114, 116, and 118).

A variety of processes and methods may be used for transmissions in thewireless communication system 100 between the AP 104 and the STAs. Forexample, signals may be sent and received between the AP 104 and theSTAs in accordance with OFDM or orthogonal frequency-division multipleaccess (OFDMA) techniques. If this is the case, the wirelesscommunication system 100 may be referred to as an OFDM/OFDMA system.Alternatively, signals may be sent and received between the AP 104 andthe STAs in accordance with CDMA techniques. If this is the case, thewireless communication system 100 may be referred to as a CDMA system.In an aspect, the wireless communication system 100 may support MIMOtransmissions, including single-user MIMO and multi-user MIMO. Thewireless communication system 100 may also support multi-user OFDMA,etc.

A communication link that facilitates transmission from the AP 104 toone or more of the STAs may be referred to as a downlink (DL) 108, and acommunication link that facilitates transmission from one or more of theSTAs to the AP 104 may be referred to as an uplink (UL) 110.Alternatively, a downlink 108 may be referred to as a forward link or aforward channel, and an uplink 110 may be referred to as a reverse linkor a reverse channel. In some aspects, DL communications may includeunicast or multicast traffic indications.

The AP 104 may suppress adjacent channel interference (ACI) in someaspects so that the AP 104 may receive UL communications on more thanone channel simultaneously without causing significant analog-to-digitalconversion (ADC) clipping noise. The AP 104 may improve suppression ofACI, for example, by having separate finite impulse response (FIR)filters for each channel or having a longer ADC backoff period withincreased bit widths.

The AP 104 may act as a base station and provide wireless communicationcoverage in a basic service area (BSA) 102. A BSA (e.g., the BSA 102) isthe coverage area of an AP (e.g., the AP 104). The AP 104 along with theSTAs associated with the AP 104 and that use the AP 104 forcommunication may be referred to as a basic service set (BSS). It shouldbe noted that the wireless communication system 100 may not have acentral AP (e.g., AP 104), but rather may function as a peer-to-peernetwork between the STAs. Accordingly, the functions of the AP 104described herein may alternatively be performed by one or more of theSTAs.

The AP 104 may transmit on one or more channels (e.g., multiplenarrowband channels, each channel including a frequency bandwidth) abeacon signal (or simply a “beacon”), via a communication link such asthe downlink 108, to other nodes (STAs) of the wireless communicationsystem 100, which may help the other nodes (STAs) to synchronize theirtiming with the AP 104, or which may provide other information orfunctionality. Such beacons may be transmitted periodically. In oneaspect, the period between successive transmissions may be referred toas a superframe. Transmission of a beacon may be divided into a numberof groups or intervals. In one aspect, the beacon may include, but isnot limited to, such information as timestamp information to set acommon clock, a peer-to-peer network identifier, a device identifier,capability information, a superframe duration, transmission directioninformation, reception direction information, a neighbor list, and/or anextended neighbor list, some of which are described in additional detailbelow. Thus, a beacon may include information that is both common (e.g.,shared) amongst several devices and specific to a given device.

In some aspects, a STA (e.g., STA 114) may be required to associate withthe AP 104 in order to send communications to and/or to receivecommunications from the AP 104. In one aspect, information forassociating is included in a beacon broadcast by the AP 104. To receivesuch a beacon, the STA 114 may, for example, perform a broad coveragesearch over a coverage region. A search may also be performed by the STA114 by sweeping a coverage region in a lighthouse fashion, for example.After receiving the information for associating, either from the beaconor probe response frames, the STA 114 may transmit a reference signal,such as an association probe or request, to the AP 104. In some aspects,the AP 104 may use backhaul services, for example, to communicate with alarger network, such as the Internet or a public switched telephonenetwork (PSTN).

In an aspect, the AP 104 may include one or more components forperforming various functions. For example, the AP 104 may include a TWTcomponent 124 to perform procedures related to TWToperations/scheduling. In an aspect, TWT component referred to hereinmay be a scheduling component. In one example, the TWT component 124 maybe configured to receive, from a second wireless device, a first messagethat includes a first trigger field. The first trigger field mayindicate whether the first message includes a request for a triggermessage to be sent by the first wireless device at a start of a TWTservice period. The TWT component 124 may be configured to determine aTWT schedule based on the received first message. The TWT component 124may be configured to transmit a second message to the second wirelessdevice. The second message may include the TWT schedule and a secondtrigger field based on the determined TWT schedule. The second triggerfield may indicate whether the AP 104 will transmit the trigger messageat the start of the TWT service period (or during the TWT serviceperiod). In an aspect, the AP 104 may transmit one or more triggermessages during the TWT service period. The trigger message is a framethat may enable the one or more intended recipients to transmit messagesor frames to the transmitter of the trigger message after a determinedperiod of time after the trigger message is received (e.g., after ashort interfrace space (SIFS)), for example, as an immediate response tothe trigger message in which the frames may be sent in single user (SU)mode or multi-user (MU) mode. In another example, the TWT component 124may be configured to determine a TWT schedule and to broadcast a messagethat may include the determined TWT schedule to one or more wirelessdevices. The message may include a broadcast indicator that indicatesthe TWT schedule is a broadcast TWT schedule. In yet another example,the TWT component 124 may be configured to receive a message from asecond wireless device that indicates an intention of the secondwireless device to switch to an operating mode that is one of an activemode, a power save mode, or a TWT power save mode. During the TWT powersave mode, the second wireless device may enter an awake state duringTWT service periods and may enter a doze state outside of the TWTservice periods. In this example, the TWT component 124 may beconfigured to store the operating mode associated with the secondwireless device and to transmit to the second wireless device anacknowledgment of the operating mode switch.

In another aspect, the STA 114 may include one or more components forperforming various functions. For example, the STA 114 may include a TWTcomponent 126 to perform procedures related to TWT operation/scheduling.In one example, the TWT component 126 may be configured to transmit afirst message that includes a first trigger field to a second wirelessdevice. The first trigger field may indicate whether the first messageincludes a request for a trigger message to be sent by the secondwireless device at a start of a TWT service period or during a TWTservice period. The TWT component 126 may be configured to receive asecond message from the second wireless device. The second message mayinclude a second trigger field based on the first message, and thesecond trigger field may indicate whether the second wireless devicewill transmit the trigger message at the start of the TWT serviceperiod. In another example, the TWT component 126 may be configured toreceive from a second wireless device a message that includes a TWTschedule. The message may include a broadcast indicator that indicatesthe TWT schedule is a broadcast TWT schedule. The TWT component 126 maybe configured to determine one or more TWTs for the first wirelessdevice based on the TWT schedule. In another example, the TWT component126 may be configured to determine whether to switch to an active mode,a power save mode, or a TWT power save mode. During the TWT power savemode, the STA 114 may enter an awake state during TWT service periodsand may enter a doze state outside of the TWT service periods. In thisexample, the TWT component 126 may be configured to transmit a messageto a second wireless device based on the determination.

In Wi-Fi networks, an AP often serves multiple STAs within a BSS asillustrated in FIG. 1. When STAs (e.g., STAs 112, 114, 116, 118) havedata to transmit or receive, STAs exchange UL/DL frames with the AP(e.g., in a multi-user context). The UL/DL frames refer to UL only, DLonly, or both. To perform data transmission or reception, STAs may needto receive a trigger frame from the AP to enable the UL/DL exchange. Atrigger frame may contain a set of resource allocations for the UL/DLexchange. To receive the trigger frame, a STA may need to be in an awakemode/state for unknown periods of time to wait for a trigger frame.Potentially long and frequent periods spent waiting for a trigger frameincreases power consumption of the STA. As such, a need exists to reducepower consumption by lowering the airtime needed for UL/DL frameexchanges. One solution is to implement a target wake time (TWT)scheduling protocol in which devices (e.g., STAs or APs) may bescheduled to sleep and wake up at specific times to perform UL/DLexchanges and trigger frames may be scheduled for transmission atpredetermined or negotiated times. When a STA or an AP is not scheduledto be awake to receive trigger frames, for example, the STA or the APcan be in sleep mode (or power save mode) to conserve power. The TWTscheduling protocol is beneficial to any scheduling mechanism that maybe negotiated between devices or dictated by one device to scheduleintervals of time during which to exchange information between two ormore devices. While the above description is related to powerconsumption aspects, other benefits of scheduling are obvious to oneskilled in the art, such as contention reduction, hidden nodemitigation, interference management, etc.

To facilitate improved power management protocols and techniques forWi-Fi networks, three main topics are provided below. The first topicrelates to a solicit TWT protocol that enables a first wireless deviceto negotiate with a second wireless device to determine an individualTWT schedule that will indicate when the first wireless device will wakeup to communicate with the second wireless device. The second topicrelates to a broadcast TWT protocol in which a first wireless device,such as for example an AP, may determine a TWT schedule for one or morewireless devices (e.g., multiple STAs). The TWT schedule in a broadcastTWT protocol may not be negotiated. Instead, other wireless devices thatwant to communicate with the first wireless device will wake upaccording to the times provided in the broadcasted TWT schedule. Theother wireless devices may also communicate with the first wirelessdevice according to the parameters provided by the first wirelessdevice. Both the solicit TWT and broadcast TWT protocols may useimplicit or periodic TWT schedules (in which a first TWT may beexplicitly indicated in a message and additional TWTs may be impliedfrom the first TWT and other parameters contained in the message) andexplicit or aperiodic TWT schedules (in which all TWTs associated withthe TWT schedule may be explicitly indicated in the message, and amessage for any subsequent TWTs may be delivered during a TWT serviceperiod that precedes the subsequent TWT). Finally, the third topicrelates to devices switching between different modes of operation (e.g.,active mode, a passive or power save mode, and/or a TWT power save mode)to save power. In particular, as further described below, the TWT powersave mode is a mode of operation designed to reduce power consumptionfor wireless devices operating in accordance with a TWT agreement orschedule.

In an aspect, to enable wireless devices to negotiate and/or transmitTWT schedules, a signaling mechanism that identifies the differentparameters associated with TWT scheduling is needed. FIG. 2 provides oneexemplary diagram of a TWT element for TWT scheduling. In the exemplarydiagram, one or more of the fields shown in the figure may be optionallypresent, depending on the parameters being delivered. As an example, inTWT setup the TWT element may not contain the TWT group assignmentfield, the NDP paging field and/or the OFDMA channel bitmaps field.Other fields may also not be present in the exchanged TWT element. Othervariations of the TWT element inline with the teachings herein are alsoprovided in subsequent figures.

FIG. 2 is an exemplary diagram of a TWT element 200 for supportingtarget wake time and trigger frame scheduling. To enable a TWTscheduling, an AP and a STA, for example, may negotiate a target waketime using a TWT element that provides the necessary signaling betweendevices to schedule one or more target wake times and theircorresponding parameters. The TWT element may be transmitted in anindividually addressed management frame that can be of type action,action no ack, (re)association request/response, probe request response,etc., when the TWTs are negotiated between the first wireless device andthe second wireless device, e.g., during a TWT setup phase. In anotherembodiment, for a broadcast TWT, the TWT element may be transmitted in abroadcast management frame that can be of type Beacon, or TIM Broadcastframe, etc. In this embodiment the TWT element provides non-negotiatedschedules (e.g., broadcast TWT schedules) as described further below.

In an aspect, the STA requesting the TWT schedule may be referred to asthe TWT requester, and the AP responding to the request may be known asthe TWT responder. In this embodiment, the TWT schedule and parametersare provided during the TWT setup phase and renegotiation/changes of TWTschedules are signaled via individually addressed frames that containthe updated TWT parameters. These frames can be management frames asdescribed above, control frames or data frames that carry a fieldcontaining the updated TWT schedule and its related parameters. Inanother aspect, two STAs may negotiate a TWT schedule and one STA may bethe TWT requester and the other STA may be the TWT responder.

Referring to FIG. 2, in the TWT element 200, an element ID (e.g., 1octet in length) may indicate that an information element is a TWTelement. A length field (e.g., 1 octet) may indicate the length of theTWT element 200 starting from the control field until the end of the TWTelement (e.g., the end of the OFDMA channel bitmaps field). The TWTelement 200 may include a target wake time field (e.g., 8 octets orless), a TWT group assignment field (e.g., 9, 3, 2, or 0 octets), anominal minimal wake duration field (e.g., 1 octet), a TWT wake intervalmantissa (e.g., 2 octets), a TWT channel field (e.g., 1 octet), an NDPpaging field (e.g., 0 or 4 octets) and/or an OFDMA channel bitmaps field(e.g., 0, 1, 2 to 8 Octets). In certain embodiments, the length fieldmay indicate a length of a TWT element that carries multiple groups orinstances of these fields (e.g., multiple groups of the fields from atleast one of the Control, Request Type, . . . , up to the OFDMA channelbitmaps field as shown in the TWT element 200). In such embodiments, theTWT element 200 may contain TWT parameters for one or more TWTnegotiations or indications as described herein. Each of the TWTnegotiations contained in the TWT element may be identified by a uniqueTWT flow identifier. In certain embodiments, the one or more groups offields may be related to non-negotiated TWTs (e.g., broadcast TWTs) asdescribed further below.

Referring to FIG. 2, a request type field (e.g., 2 octets) may indicatea type of TWT request. The request type field may include multiplefields (or subfields). The fields may include a TWT request field (e.g.,1 bit), a TWT setup command field (e.g., 3 bits), a trigger field (e.g.,1 bit), an implicit field (e.g., 1 bit), a flow type (e.g., 1 bit), aTWT flow identifier (e.g., 3 bits), a wake interval exponent (e.g., 5bits), and/or a TWT protection field (e.g., 1 bit).

The TWT request field may indicate whether the TWT element 200represents a request. If TWT request field has a value of 1, then theTWT element 200 may represent a request to initiate TWTscheduling/setup. Otherwise, if the TWT request field has a value of 0,then the TWT element 200 may represent a response to a request toinitiate TWT scheduling/setup (solicit TWT), an unsolicited TWT (whichis a response to initiate a TWT scheduling which is conceptually similarto the solicited TWT with the exception that the TWT requester STA didnot send a TWT request to solicit this TWT response), and/or anon-negotiable TWT scheduling message (or a broadcast TWT message). Inthe case of the non-negotiable TWT (broadcast TWT), one or more of theabove mentioned fields (including the TWT request field) may not bepresent in the TWT element as discussed further below).

The TWT setup command field may indicate the type of TWT command. In aTWT request, the types of TWT commands may indicate the following:request TWT (the TWT field contains zeros because the TWT responderspecifies the TWT value; e.g., field set to 0), suggest TWT (the TWTrequester suggests a TWT value; e.g., field set to 1), and demand TWT(the TWT requester demands a TWT value; e.g., field set to 2). In a TWTresponse, the types of TWT commands may include TWT grouping (the TWTresponder suggests TWT group parameters that are different from thesuggested or demanded TWT parameters of the TWT requester; e.g., fieldset to 3), accept TWT (the TWT responder accepts the TWT request withthe TWT parameters indicated; e.g. field set to 4), alternate TWT (theTWT responder suggests TWT parameters that are different from theparameters suggested or demanded by the TWT requester; e.g., field setto 5), dictate TWT (the TWT responder demands TWT parameters that aredifferent from the parameters suggested or demanded by the TWTrequester; e.g., field set to 6), or reject TWT (the TWT responderrejects the TWT setup; e.g. field set to 7).

In a TWT response, the TWT command may indicate an unsolicited response(e.g., the TWT responder may demand the recipient to follow the TWTschedule contained in the element), a broadcast TWT (the TWT responderis scheduling the TWT for any STA that is reading the element), etc. Inparticular, for an unsolicited response, the TWT element 200 may includea value of dictate TWT in the TWT command field and the TWT requestfield may be set to 0. The unsolicited TWT is an individually addressedframe that is intended for a specific STA (whereas a broadcast TWT maybe for multiple STAs and may be carried in a broadcast frame such as,for example, a beacon. Further, the unsolicited TWT may typicallyinvolve a frame exchange in which the STA receiving the unsolicited TWTmay respond with an ACK, whereas broadcast TWTs may not be acknowledged.

In an aspect, a TWT responder, who receives a TWT request from a TWTrequester and whose value of the TWT wake interval is equal to the TWTrequester's listen interval, may respond to the TWT request with eitheran accept TWT or a reject TWT in the TWT command field. In the case ofan accept TWT, the accept TWT may include the value of the allocatedfirst target beacon transmit time in the TWT wake time field and thevalue of the listen interval between consecutive target beacon transmittimes (TBTTs) in the TWT wake interval mantissa and the TWT wakeinterval exponent fields. In this aspect the TWT request/TWT responsemechanism may be used by the requesting STA to identify which of thebroadcast frames that contain the broadcast TWT schedule (e.g., beaconframes) it will wake to receive. In certain embodiments, a value of theTWT flow identifier may be reserved for this purpose (negotiation ofTBTTs) to differentiate it from a TWT setup that negotiates TWTschedules). As an example, either the value 0 or 7 of the TWT flowidentifier may be used for this purpose (negotiation of TBTTs). In thisaspect, either of these values shall not be used for the purpose ofnegotiating TWT schedules.

If sent in a TWT request, the trigger field may indicate whether arequest for a target wake time includes a request for a trigger frame tobe sent by the TWT responder at the start or during the TWT serviceperiods that correspond to the requested TWT schedule. In an aspect, thetrigger frame may be transmitted up to the duration of the TWT serviceperiod that corresponds to the scheduled TWT and one or more triggerframes may be scheduled by the TWT responder. If sent in a TWT response,the trigger field may indicate whether a response to a request for atarget wake time indicates whether one or more trigger frames will besent at a scheduled TWT. The one or more trigger frames may be sentwithin the boundaries of the TWT service period duration that correspondto the requested TWT schedule. For example, in a TWT request, if thetrigger field has a value of 0, then the TWT request may not request atrigger frame, but if the trigger field has a value of 1, then the TWTrequest may request a trigger frame. In a TWT response, if the triggerfield has a value of 0, then no trigger frame will be sent, but if thetrigger field has a value of 1, then at least one trigger frame may betransmitted at or during a scheduled TWT service period. In certainembodiments, the trigger field may be included in any of the fields inthe TWT element or in any other fields of other elements used forproviding scheduling information.

The implicit field may indicate whether the next TWT is implicitlycalculated or explicitly signaled. For example, if the implicit fieldhas a value of 1, then the next TWT is implicitly calculated by the TWTrequester (and TWT responder) during a TWT service period of a scheduledTWT (in certain embodiments as identified by the TWT flow identifier).For example, the subsequent or next TWT may be determined based on thevalue of the TWT (e.g., as indicated in the TWT element 200) of thecurrent TWT service period plus a multiple of the TWT wake interval(e.g., TWT period=TWT wake interval mantissa*2^(wake interval exponent),such that next TWT=current TWT+TWT period). This allows periodicscheduling of the TWTs, which is simple and flexible for normaloperations. In an aspect, a wireless device that has an implicit TWTschedule (or agreement) with another wireless device may not generate ablock acknowledgment TWT frame (BAT) frame, a TWT acknowledgment (TACK)frame, or a short TWT acknowledgment (STACK) frame for subsequent TWTstart times associated with the same TWT schedule. If the implicit fieldhas a value of 0, then the next TWT may be explicitly signaled by theTWT responder during a TWT service period. The TWT responder maytransmit a BAT or TACK or STACK frame, each of which is a controlresponse frame that may contain next TWT information.

In certain embodiments, the TWT responder may transmit a TWT informationframe (e.g., an action frame or action no ack frame) that containssimilar TWT information. The frames may include a partial time stamp(containing a partial value of the TSF timer of the TWT responder) and anext TWT that indicates when the next TWT is scheduled (e.g., the nextTWT is scheduled in 2 or 5 seconds from the start of the TWT of thecurrent TWT service period).

In another configuration, within an implicit TWT agreement, either theTWT responder or TWT requester may transmit a TWT information frame forrescheduling the next TWT. The TWT information frame may include aresponse requested subfield set to 0 and the next TWT request subfieldset to 0. In an aspect, the TWT information frame may indicate a nonzeronext TWT in the next TWT subfield when the TWT information frame istransmitted by the TWT responder. In another aspect, the TWT informationframe may include indicate a suspension of the TWT agreement (or all TWTagreements) when the next TWT subfield is not present and the TWTinformation frame is transmitted by the TWT requester. In anotheraspect, the TWT information frame may indicate a resumption of thepreviously suspended TWT agreement (or all TWT agreements) when the nextTWT subfield is present and the TWT information frame is transmitted bythe TWT requester. In this aspect, the next TWT subfield may include thenext TWT, selected from the previously negotiated implicit TWT, at whichthe implicit TWT agreement is resumed. In another embodiment, anindication in any frame transmitted by the TWT requester to the TWTresponder may provide such indication. As an example, a subfield in theMAC header (e.g., within the high efficiency (HE) variant of the highthroughput (HT) Control field) of a frame transmitted to the TWTresponder may indicate a suspension of the TWT agreement(s) if set to 1and may indicate a resumption of the TWT agreement(s) if set to 0, orvice versa.

The TWT flow type may indicate the type of interaction between the TWTrequester and the TWT responder at the TWT. In an aspect, the TWTrequester may set the TWT flow type. For example, a value of 0 in theTWT flow type may indicate an announced TWT in which the TWT requesterannounces itself at the start of a TWT SP by transmitting a power savepoll (PS-Poll) frame or an automatic power save delivery (APSD) triggerframe to signal the awake state of the TWT requester to the TWTresponder before a frame is sent from the TWT responder to the TWTrequester. In an aspect, the TWT responder may not send frames to a TWTrequester without knowing the power state of the TWT requester in orderto avoid transmitting to the TWT requester when the TWT requester is ina doze state. In another example, a value of 1 in the flow type mayindicate an unannounced TWT. In an unannounced TWT, the TWT requestermay not need to announce itself. The TWT responder may assume that theTWT requester is awake. The TWT responder may transmit one or more DLframes to the TWT requester at the TWT without waiting to receive aPS-poll or an APSD trigger frame from the TWT requester.

In another aspect, a TWT responder may set the TWT flow type to 0 toindicate that the TWT responder may transmit a frame to the TWTrequester at a TWT without waiting to receive a PS-Poll or APSD triggerframe from the TWT requester. In another aspect, the TWT responder mayset the TWT flow type to 1 to indicate that the TWT responder may nottransmit a frame to the TWT requester within the TWT service perioduntil the TWT responder has received a PS-Poll or APSD trigger framefrom the TWT requester.

The TWT flow identifier may contain a 3-bit value. In one aspect, forsolicit TWTs or unsolicited TWTs (e.g., TWT elements contained inindividually addressed frames), the TWT flow identifier may identifyspecific information for a TWT request uniquely from other requests madebetween the same TWT requester and the TWT responder pair. In certainaspects, as described above, a value of the TWT flow identifier may bereserved for the purpose of negotiation the TBTTs for broadcast TWToperation, e.g., a value 0 or value 7). In another aspect, such as for aTWT element that carries information for one or more TWT parameter sets,each of which includes information related to one or more TWT SPs thatare broadcast TWT SPs (e.g., a broadcast TWT element that is carried ina broadcast frame (or in general group addressed frame)), the TWT flowidentifier may indicate the types of flows that may be allowed inresponse to a scheduled trigger frame during the TWT service periodswhen the trigger field of the TWT element is set to 1 and the type offlows that may be allowed during the TWT SPs when the trigger field ofthe element is set to 0. In one example, when the TWT flow identifier is0, wildcard or random OFDMA allocation access from unassociated STAs maybe allowed. In another example, when the TWT flow identifier is 1,wildcard or random OFDMA allocation access from associated STAs may beallowed. In another example, when the TWT flow identifier is 2,scheduled access for associated STAs in power save mode may be allowed.In another example, when the TWT flow identifier is 3, voice traffic maybe allowed. In yet another example, when the TWT flow identifier is 4,video traffic may be allowed, etc. In another example, a value of theTWT flow identifier may indicate that (T)DLS (direct link setup ortunneled direct link setup) traffic is allowed (e.g., frames exchangedbetween STAs (e.g., neither of which is the STA that sent the triggerframe when the trigger field of the TWT element is 1). In certainaspects, the above described functionalities of the TWT flow identifiermay be incorporated in a different subfield within the TWT element. Inother embodiments, such as when the TWT service period that is not abroadcast TWT service period, the TWT flow identifier subfield maycontain a value that identifies the specific information associated withthe TWT request uniquely from other requests made between the same TWTrequester and TWT responder pair.

The TWT protection field may indicate whether a TWT is protected orunprotected. A TWT requester may set the TWT protection field to 1 torequest the TWT responder to provide protection for the set of TWTservice periods corresponding to the requested TWT ID by allocating oneor more restricted access windows (RAWs) that restrict access to themedium during the TWT service periods corresponding to the TWTs. Incertain embodiments, a TWT protection field equal to 1 indicates arequest or response to commit (e.g., shall) using network allocationvector (NAV) protection mechanisms to protect the access to the mediumduring the corresponding TWT service periods. A TWT requester sets theTWT protection field to 0 if the TWT protection by RAW allocation is notrequested for the corresponding TWTs. For an unprotected TWT, the TWTresponder may protect the TWT service periods using a NAV protectionmechanisms (or other similar mechanisms). That is, each STA may includea NAV and may increase the NAV and delay transmitting while other STAsare transmitting.

In certain aspects, the TWT responder that has set the TWT protectionfield to 1 may send a NAV setting frame approximately at the start ofthe TWT service periods that correspond to the particular scheduled TWT.For example, the NAV setting frame can be a CTS message. In theseaspects, any STA that receives the frame and is not scheduled to accessthe medium during the TWT service period that is covered by the NAVduration of the NAV setting frame shall set their NAV and not access themedium for the specified amount of time. On the other hand, any STA thatreceives the frame and is scheduled to access the medium during the TWTservice period should ignore the NAV settings dictated by the CTS toself frame (in certain embodiments STAs can reset their NAV counterseven though the counters were set by other received frames).

In an aspect, the NAV or the NAV setting frame may be ignored by STAsthat are accessing the medium during the TWT service period (e.g., forcertain frames only such as multi-user or single user, short packetsize, etc.)

In a TWT request, the TWT wake interval may be the average time that theTWT requester expects to elapse between successive TWT service periods.In a TWT response, the TWT wake interval may be the average time thatthe TWT responder expects to elapse between successive TWT serviceperiods. When transmitted by a TWT requester, the TWT field may containa positive integer which corresponds to a time at which the TWTrequester requests to wake, or a value of zero when the TWT setupcommand field contains the value corresponding to the command “RequestTWT.” When transmitted by a TWT responder, the TWT field may contain avalue that corresponds to a time at which the TWT responder requests theTWT requester to wake. The TWT group assignment field may provideinformation to a TWT requester about the TWT group to which the TWTrequester is assigned. The nominal minimum wake duration field mayindicate the minimum amount of time that the TWT requester expects thatthe TWT requester needs to be awake in order to complete the frameexchange associated with the TWT flow identifier for the period of theTWT wake interval, where the TWT wake interval is the average that theTWT requester expects to elapse between successive TWT service periods.The TWT wake interval mantissa may be set to the value of the mantissaof the TWT wake interval value in microseconds, base 2.

When transmitted by a TWT requester, the TWT channel field may contain abitmap (or other information) indicating which channel or channels theTWT requester wants to use as temporary primary channels or as channelsto be used for DL and/or UL MU transmissions (MU OFDMA or MIMO) duringthe TWT service period that corresponds to the scheduled TWT. Whentransmitted by a TWT responder, the TWT channel field may contain abitmap (or other information) indicating which channels the TWTrequester is allowed to use as temporary channel or channels or aschannels to be used for DL and/or UL MU transmissions (MU OFDMA or MIMO)during the TWT service period. In certain embodiments, the channel widthof each of the channels identified by the bits in the TWT channel bitmapmay be 20 MHz. As such, in one configuration, the TWT channel field mayindicate the channel and the channel width that the TWT requester or theTWT responder expects to be used for exchanging frames during a TWTservice period. A single user physical layer convergence procedure(PLCP) protocol data unit (PPDU) exchanged between devices during a TWTservice period may not exceed the negotiated channel width. A PLCPservice data unit (PSDU) contained in MU PPDUs, for example, may betransmitted within the negotiated channel(s) and may not exceed thewidth of the negotiated channel. For example, if the negotiated channelhas an upper bit equal to 1, then MU PSDUs exchanged during the TWTservice period may be located in the upper 20 MHz of a 160 MHz channel.This configuration enables STAs to dynamically negotiate operatingprimary channel/width and also indicate which MU resource is preferred.If STAs prefer not to use this signaling, then the STAs may set the TWTchannel field to the BSS primary channel and set the channel width tothe width of the BSS primary channel. In another configuration, the TWTchannel field may be set to 0 and indicate nothing.

In another aspect, the TWT element 200 may additionally include an OFDMAchannel bitmaps field. In certain embodiments this field may provide abitmap of subchannels for the channels indicated in the TWT channelfield. The OFDMA channel bitmaps field may contain a bitmap ofsubchannels. In one aspect, the OFDMA channel bitmaps field may containone or more bitmaps (one for each of the bits set to 1 in the TWTchannel field) each of which may be associated with one channelindicated in the TWT channel bitmap. Each bitmap may contain 8 bits eachof which may identify one subchannel (e.g., an OFDMA channel) of channelwidth 2.5 MHz, or less) of the 20 MHz channel of the corresponding bitin the TWT channel bitmap. The number of OFDMA channel bitmaps may beequal to the number of non-zero bits in the TWT channel field precedingthe OFDMA channel bitmaps field. The n-th OFDMA channel bitmap field maybe a mapping of the subchannels of the n-th channel located at the n-thposition in the TWT channel bitmap. Note that for exemplary purposes,some values of channel widths and field sizes are described, any valuecan be used for covering different bandwidths, channels, and subchannelunits. As such, greater flexibility may be added by defining OFDMAchannel bitmaps for each of the TWT channels indicated in the TWTchannel field. An OFDMA channel bitmap enables a TWT requester toindicate a preference for which channel to be allocated during the UL/DLmulti-user operation in the TWT channel and eventually in the OFDMAchannel bitmaps. The TWT responder can agree with the TWT requester'ssuggestion or suggest other channels or a subset of the indicatedchannels in a TWT response.

As discussed above, the TWT element 200 may be transmitted in differenttypes of frames. The frames may be individually addressed or groupaddressed frames. In one aspect, the TWT element 200 may be transmittedin an action frame (e.g., either an action ACK or action no ack frame)or other frame types such as an association request/response and/orprobe request/response frames. In other aspects, the TWT element 200 maybe transmitted in a beacon frame or in another management frame. In anaspect, the aforementioned parameters or fields in the TWT element 200,including the TWT, the TWT Wake Interval Mantissa, and the TWT channelparameters, may be negotiated between devices during TWT setup, whichmay be performed using individually addressed frames exchanged betweenthe TWT requester and TWT responder. In another aspect, the bit lengthsof each field/subfield described above are provided for exemplarypurposes and are not intended to limit the scope of the TWT element 200.

Solicited TWT Scheduling

FIG. 3 includes an exemplary diagram 300 of a wireless networkimplementing solicit TWT scheduling and an exemplary timing flow diagram350 for TWT operation. The diagram illustrates an AP 302 broadcasting ortransmitting within a BSS 304. STAs 306, 308, 310 are within the BSS 304and are served by the AP 302. The STAs 306, 308, 310 and the AP 302 mayperform TWT scheduling.

In one configuration, the STA 306 and the AP 302 may negotiate the TWTscheduling. In this configuration, the STA 306 may act as the TWTrequester and initiate TWT setup with the AP 302 (although STA 306 andthe AP 302 may also reverse roles). During TWT setup, the STA 306 maytransmit a first message 312 (e.g., an action frame, association frame,or another frame) to the AP 302, which may act as the TWT responder. Thefirst message 312 may include a TWT element (e.g., the TWT element 200illustrated in FIG. 2). The first message 312 may include a firstelement ID identifying the TWT element 200. The first message 312 mayinclude a first TWT request field having a value of 1 to indicate thatthe TWT element is a TWT request. The first message 312 may include afirst trigger field with a value of 0 if the STA 306 does not request atrigger frame to be sent by the AP 302 at the start of or during a TWTservice period. In another aspect, the first message may include a firsttrigger field with a value of 1 if the STA 306 includes a request for atrigger message to be sent by the AP 302 at the start of or during theone or more TWT service periods that correspond to the requested TWTschedule. In another aspect, the STA 306 may set a first TWT setupcommand to “Request TWT” to enable to AP 302 to set a TWT for the STA306. In another aspect, the STA 306 may set the first TWT setup commandto “Suggest TWT” to indicate a suggested/requested TWT to the AP 302. Inaddition, the STA 306 may set the other parameters of the TWT request toindicate other parameters for the request. For example, the STA 306 mayset the implicit field to 1 to indicate a request for an implicit TWTschedule (e.g., periodic) or to 0 to indicate an explicit TWT. In anaspect, the STA 306 may set the implicit field to 1 and the NDP pagingindicator subfield of the element to 0. The STA 306 may set the flowtype to indicate announced TWT (e.g., the TWT requester intends to bethe first to send a frame (e.g., PS-Poll or APSD trigger frame)following the trigger frame) or unannounced TWT (e.g., the TWT responderis to assume the STA be in awake state and to send other frames to theSTA in DL). The STA 306 may also indicate a preferred channel and/orpreferred subchannels in the TWT channel field for use during thescheduled TWT. In an aspect, the STA 306 may further indicate preferredOFDMA subchannels in an OFDMA subchannel bitmap field within the firstmessage 312.

After receiving the first message 312 from the STA 306, the AP 302 maydetermine whether to schedule one or more target wake times based on thefirst message 312. The AP 302 may determine whether to schedule TWTs forthe STA 306 based on the number of STAs and/or the amount of datatraffic within the BSA 304. For example, if the AP 302 detects a largenumber of STAs (e.g., 4) in the BSS 304, the AP 302 may improve channelcontention by spreading out the wake up times of STAs if the STAs areoperating in single user (SU) mode or concentrate the STAs wake up timesif they are operating in multi-user (MU) mode. By contrast, if the AP302 detects a small number of STAs (e.g., 1 or 2), the AP 302 mayschedule the target wake times closely so that resources are not wastedand data rates may be high. However, the AP 302 may want to improvepower save of the STAs in which case the AP 302 may account for theSTAs' suggestions of the TWT allocations etc. Similarly, if the AP 302determines that the medium is busy, the AP 302 may spread out the wakeup times of the STAs to reduce traffic. If the medium is not busy, theAP 302 may schedule the target wake times closely. In an aspect, if theAP 302 determines that the medium is not busy and the first message 312includes a suggested TWT, the AP 302 may determine to accept the TWTrequested in the first message 312. In another aspect, if the medium isbusy, the AP 302 may determine to provide a scheduled TWT that isdifferent from the suggested/requested TWT of the STA 306. In yetanother aspect, the AP 302 may determine not to schedule a TWT for theSTA 306. In addition the AP 302 may allocate multiple STAs with similarrequests in terms of traffic schedule, pattern, quality of service (QoS)requirements, power save requirements, feedback in the same TWT scheduleso that the AP 302 can exchange traffic with the STAs using MUtransmissions that are triggered by trigger frames.

After receiving the first message 312, the AP 302 may determine whetherto send one or more trigger frames to the STA 306 based on the value ofthe first trigger field included in the first message 312. If the valueof the first trigger field in the first message 312 is 0, then the AP302 may determine not to send a trigger frame at the start of or duringthe TWT service period. If the value of the first trigger field in thefirst message 312 is 1, then the AP may determine to send one or moretrigger frames at the start of or during the one or more TWT serviceperiods based on the medium status (e.g., amount of traffic), the numberof STAs in the BSA 304, and/or any other TWT requests from other STAs.The AP 302 may transmit a second message 314 to the STA 306. The secondmessage 314 may be a TWT response to the TWT request (e.g., the firstmessage 312) transmitted by the STA 306 (solicit TWT setup). In anotherembodiment, the second message 314 may be a TWT response that may besent without receiving any TWT requests by the STA 306 (unsolicited TWTsetup). The second message 314 may include a second trigger field basedon the first message 312. The second trigger field may indicate whetherthe AP 302 will transmit one or more trigger frames at a scheduled TWTof the TWT service period. For example, if the first trigger field inthe first message 312 has a value of 0, then the second trigger field inthe second message 314 may have a value of 0. But if the first triggerfield in the first message 312 had a value of 1, then the second triggerfield in the second message 314 may have a value of 1 if the AP 302determines to transmit one or more trigger frames at one or morescheduled TWTs of one or more TWT service periods. The scheduled TWT maybe the same as a requested TWT in the first message 312. The scheduledTWT may also be a different TWT determined by the AP 302. In anotheraspect, the scheduled TWT may be a suggested TWT by the AP 302 such thatthe STA 306 may suggest a different TWT later (e.g., the STA 306 mayrenegotiate by transmitting another TWT request). Assuming the AP 302schedules one or more trigger frames during one or more TWT serviceperiods (e.g., TWT service periods 1, 2), the STA 306 may be able tosend data to or receive data from the AP 302 upon receiving the one ormore trigger frames. Upon receiving the second message 314, the STA 306may determine whether the second trigger field has a value of 0 or 1. Ifthe second trigger field has a value of 1, the STA 306 may wait for oneor more trigger frames to be sent at a scheduled TWT and begin an UL/DLexchange upon receiving the trigger frame. Alternatively, even if thetrigger field has a value of 1, the negotiation process may continue,and the STA 306 may negotiate for a different scheduled TWT bytransmitting another message to the AP 302 requesting a different TWT(e.g., via unicast frames). Aside from negotiating the TWT, otherparameters of TWT operation may also be negotiated (e.g., the TWT wakeinterval, the TWT channel, etc.). If the second trigger field has avalue of 0, the STA 306 may wake up at the scheduled TWT indicated inthe second message 314 but not know what to expect from the AP 302during the TWT service period. For example, when the second triggerfield has a value of 0, the AP 302 may or may not send a trigger frameat the start of the TWT service period (e.g., TWT service period 1).

Although the STA 306 has been the TWT requester in the aforementioneddisclosure, in another configuration, the AP 302 may be the TWTrequester and the STA 306 may be the TWT responder. In yet anotherconfiguration, the TWT setup and negotiation may occur between two STAs,such as the STAs 306, 308. STAs may perform TWT negotiation with eachother when engaged in device-to-device communication such as in TunneledDirect Link Setup (TDLS).

In an aspect, after TWT setup and negotiation, the STA 306 may nottransmit a frame to the AP 302 during a trigger-enabled TWT serviceperiod (e.g., a TWT service period during which the AP 302 has indicatedits intention to transmit a trigger frame by setting the trigger fieldof the TWT element exchanged during the TWT setup to 1) except when theframe is solicited by a trigger frame from the AP 302. However, if theSTA 306 has data to transmit outside of a TWT SP, then the STA 306 maycontend for the medium using lower priority enhanced distributed channelaccess (EDCA) parameters with respect to other STAs. Lower priority maybe achieved, for example, by using EDCA parameters allocated to MU STAsor to TWT STAs. Such EDCA parameters may be associated with lower accesscategories such as access category best effort (AC_BE) or accesscategory background (AC_BK), as opposed to the higher priority accesscategories such as access category video (AC_VI) or access categoryvoice (AC_VO). In an aspect, the EDCA parameters may include a minimumcontention window (CWMIN), a maximum contention window (CWMAX), anarbitration inter-frame spacing number (AIFSN), and/or a transmitopportunity (TXOP). The AC_BE and AC_BK access categories may have lessfavorable CWMIN, CWMAX, TXOP, and/or AIFSN values for medium contention.

Also, after the STA 306 negotiates an individual TWT session, the STA306 may remain awake for at least an AdjustedMinimumTWTWakeDuration(e.g., a minimum time duration associated with a TWT service period)following the TWT start time to wait for a trigger message 316 from theAP 302. In another aspect, when the STA 306 transmits the frame during atrigger enabled TWT service period based on the trigger message 316, theSTA 306 may be granted special medium access privileges (e.g., the STA306 does not contend for the medium based on EDCA access categories orparameters when the transmitted frame is a response to a trigger frame).

In another aspect, after the STA 306 has negotiated an individual TWTsession with the AP 302, the STA 306 may need not to read a beacon framefrom the AP 302 because the STA 306 may not be expected to follow abroadcast TWT, which will be further discussed below.

In essence, the TWT operation as described offers several benefits. TWToperation improves channel contention because the wake times of STAs areeither spread out for SU mode or concentrated within the same period oftime to exchange frames in MU mode. STAs may wake up during scheduledtarget wake times and go to sleep outside of a TWT service period. TWToperation also reduces power expenditure because DL/UL frame exchangeairtime is reduced.

Additionally, although the aforementioned signaling has been discussedwith respect to the TWT element (e.g., the TWT element 200 in FIG. 2),similar signaling may be utilized in a RAW parameter set (RPS). Forexample, an RPS may include one or more RAW start time fields and atrigger field. The trigger field in the RPS may indicate whether atrigger frame is to be transmitted at the start of the RAW.

Although FIG. 2 and the aforementioned description disclose a single TWTin the TWT element 200, the TWT element 200 may include one or more TWTsby adjusting the value of the length field of the TWT element 200. Thus,different TWT flows may be associated with different device target waketimes. Furthermore, the TWT element 200 may schedule additional TWTs ona periodic basis. For example, a next scheduled TWT may be implicitlycalculated when the implicit field, as discussed above, is set to 1. Thenext scheduled TWT may be calculated based on the scheduled TWT plus amultiple of the TWT wake interval. In this aspect, a scheduled TWT maybe associated with multiple later occurring scheduled TWTs, and thescheduled TWT may be associated with a corresponding TWT service periodand with multiple later occurring TWT service periods associated withthe later occurring scheduled TWTs.

FIG. 4 is a flowchart of an example method 400 of requesting TWTscheduling. The method 400 may be performed using an apparatus (e.g.,the AP 302, the STA 306, or the wireless device 1302, infra, forexample). Although the method 400 is described below with respect to theelements of wireless device 1302 of FIG. 13, infra, other components maybe used to implement one or more of the steps described herein.

At block 405, the apparatus may transmit a first message that includes afirst trigger field to a second wireless device. The first trigger fieldmay indicate whether the first message includes a request for a triggermessage to be sent by the second wireless device at a start of a TWTservice period For example, referring to FIG. 3, the apparatus may bethe STA 306, and the second wireless device may be the AP 302. The STA306 may transmit the first message 312 that includes the first triggerfield to the AP 302. The first trigger field has a value of 1,indicating that the first message 312 includes a request for a triggerframe to be sent by the AP 302. In this example, the first trigger fieldhaving a value of 1 is (or indicates) a request for a trigger frame. Thefirst message 312 also includes a suggested TWT of a TWT service period.In another example, the requested TWT may be a null value, indicatingthat no specific time is requested for TWT and that the AP 302 is freeto select a scheduled TWT time. In an aspect, the first message 312 mayinclude a TWT channel field that indicates a channel and a channel widththat the STA 306 may use for communicating with the AP 302 during theTWT service period.

At block 410, the apparatus may receive a second message from the secondwireless device. The second message may include TWT parameters and asecond trigger field based on the first message, and the second triggerfield may indicate whether the second wireless device will transmit thetrigger message at the start of the TWT service period. For example,referring to FIG. 3, the STA 306 may receive the second message 314 fromthe AP 302. The second message 314 may include one or more fields (TWTparameters) in a TWT element and a second trigger field based on thefirst message 312. The second trigger field may have a value of 1,indicating that the AP 302 will transmit the trigger frame at ascheduled TWT of the TWT service period. In an aspect, the scheduled TWTvalue is later than the requested TWT value in the first message 312.Moreover, the first message 312 may include an OFDMA bitmap thatindicates one or more OFDMA channels and channel widths, associated withthe channels indicated in the TWT channel, for communicating with theSTA 306.

At block 415, the apparatus may determine a TWT schedule based on thereceived second message. The apparatus may determine the TWT schedule bydetermining whether the TWT schedule is an implicit TWT schedule or anexplicit TWT schedule based on the received second message and bydetermining one or more TWTs associated with the TWT schedule based onthe received second message. For example, referring to FIG. 3, the STA306 may determine whether the second message 314 indicates an implicitor explicit TWT schedule based on whether the implicit field is set to 1(implicit TWT) or to 0 (explicit TWT). If the TWT schedule is implicit,then the STA 306 may determine one or more TWTs associated with the TWTschedule based on a TWT value included in the second message 314 andbased on a TWT wake interval mantissa and a wake interval exponentincluded in the second message 314. By contrast, if the TWT schedule isan explicit TWT schedule, then the STA 306 may determine one or moreTWTs based on the TWTs included in the second message 314.

At block 420, the apparatus may determine whether to transmit to thesecond wireless device based on the determined TWT schedule. In oneconfiguration, the apparatus may determine whether to transmit bydetermining to transmit during the TWT service period only when atrigger message is received from the second wireless device or bydetermining to transmit outside of the TWT service period based on EDCAparameters associated with a best effort access category (AC_BE) or abackground access category (AC_BK). For example, referring to FIG. 3,the STA 306 may determine whether to transmit to the AP 302 based on thedetermined TWT schedule. If the STA 306 wants to transmit during a TWTservice period associated with the determined TWT schedule, then the STA306 may wait for the trigger message 316 from the AP 302 beforetransmitting to the AP 302. If the STA 306 transmits during the TWTservice period based on the trigger message 316, the STA 306 may notneed to contend for the medium using EDCA. If the STA 306 does notreceive the trigger message 316, then the STA 306 may refrain fromtransmitting during the TWT service period. In another aspect, if theSTA 306 has data for transmission outside of the TWT service period,then the STA may transmit based on an EDCA contention for lower priorityEDCA parameters associated with a best effort access category.

At block 425, the apparatus may receive a trigger message based on thedetermined TWT schedule. The trigger message may include a cascadedindicator that indicates whether the second wireless device willtransmit another trigger message after the trigger message in the TWTservice period. For example, referring to FIG. 3, the STA 306 mayreceive the trigger message 316 based on the determined TWT schedule.The trigger message 316 may include a cascaded indicator set to 0 thatindicates the AP 302 will not transmit another trigger message in theTWT service period.

At block 430, the apparatus may receive a TWT information message fromthe second wireless device. The TWT information message may include anext TWT value. For example, referring to FIG. 3, the STA 306 mayreceive a TWT information message from the AP 302. In an aspect, the TWTschedule may be an implicit TWT schedule, and the TWT informationmessage may indicate a different next TWT than what is implied based onthe TWT schedule. In another aspect, the TWT schedule may be an explicitTWT schedule indicated by the second message 314, and the TWTinformation message may indicate a next TWT value that is different fromthe TWT values indicated in the second message 314.

At block 435, the apparatus may update the TWT schedule based on thereceived TWT information message. For example, referring to FIG. 3, theSTA 306 may store and associate the new next TWT value with thedetermined TWT schedule.

At block 440, the apparatus may transmit a TWT information message tothe second wireless device. The TWT information message may indicate asuspension of an implicit TWT schedule or a resumption of the implicitTWT schedule after the implicit TWT schedule has been suspended. Forexample, referring to FIG. 3, if the TWT agreement between the STA 306and the AP 302 is an implied TWT schedule, and the STA 306 no longer hasdata to transmit, then the STA 306 may transmit a TWT informationmessage to the AP 302 signaling a suspension of the implicit TWTschedule. Subsequently, when the STA 306 has data to transmit, the STA306 may transmit a second TWT information message to the AP 302 toindicate a resumption of the suspended TWT schedule.

Although the aforementioned examples describe a STA as an apparatusperforming the steps in the method 400, an AP may also perform the stepsof the method 400. That is, the AP may be the TWT requester and the STAmay be the TWT responder. In another aspect, STAs may be engaging indevice-to-device communications, and one STA may be the TWT requesterand another STA may be the TWT responder.

FIG. 5 is a flowchart of an example method 500 of responding to arequest for, or of transmitting information related to, TWT scheduling.The method 500 may be performed using an apparatus (e.g., the STA 306,the AP 302, or the wireless device 1302, infra, for example). Althoughthe method 500 is described below with respect to the elements ofwireless device 1302 of FIG. 13, infra, other components may be used toimplement one or more of the steps described herein.

At block 505, the apparatus may receive, from a second wireless device,a first message that includes a first trigger field. The first triggerfield may indicate whether the first message includes a request for atrigger message to be sent by the apparatus at a start of a TWT serviceperiod. For example, referring to FIG. 3, the apparatus may be the AP302 and the second wireless device may be the STA 306. The AP 302 mayreceive the first message 312 from the STA 306. The first message 312may include a first trigger field set to 1, indicating that the firstmessage 312 requests a trigger frame to be sent by the AP 302. The firstmessage 312 may further include at a requested TWT for the STA 306.

At block 510, the apparatus may determine a TWT schedule based on thereceived first message. The apparatus may determine the TWT schedule bydetermining if the first trigger field in the first message includes arequest for the trigger message and by scheduling one or more TWTs forthe second wireless device if the trigger field includes the request forthe trigger message. For example, referring to FIG. 3, the AP 302 maydetermine whether to send a trigger frame to the STA 306 by determiningthat the first message 312 includes the first trigger field set to 1 andby scheduling a TWT for the STA 306. The scheduled TWT may be for animplicit TWT. In an aspect, the AP 302 may determine the TWT based onthe expected traffic on the wireless medium.

At block 515, the apparatus may transmit a second message to the secondwireless device. The second message may include the TWT schedule and asecond trigger field based on the determined TWT schedule. The secondtrigger field may indicate whether the apparatus will transmit thetrigger message at the start of the TWT service period. In one example,referring to FIG. 3, the AP 302 may transmit the second message 314 tothe STA 306. The second message 314 may include the TWT schedule and asecond trigger field having a value of 1 based on the determination tosend a trigger frame to the STA 306. The second message 314 may alsoindicate that the trigger frame will be transmitted at the scheduledTWT, which is different from the requested TWT in the first message 312.

At block 520, the apparatus may transmit a trigger message that includesa cascaded indicator. The cascaded indicator may indicate whether theapparatus will transmit another trigger message after the triggermessage in the TWT service period. For example, referring to FIG. 3, theAP 302 may transmit the trigger message 316 that includes a cascadedindicator. The cascaded indicator may be set to 1 and indicate that theAP 302 will transmit another trigger message within the same TWT serviceperiod as the trigger message 316.

At block 525, the apparatus may transmit a TWT information message thatincludes a next TWT value that is different from all TWT valuesassociated with the TWT schedule included in the second message. Forexample, referring to FIG. 3, the AP 302 may transmit a TWT informationmessage that includes a next TWT value that is different from the TWTvalues associated with the implicit TWT schedule included in the secondmessage 314. Alternatively, if the TWT schedule is an explicit TWTschedule, the AP 302 may transmit a TWT information message thatincludes a next TWT value that is different from the TWT valuesassociated with the explicit TWT schedule.

At block 530, the apparatus may receive a TWT information message fromthe second wireless device. The TWT information message may indicate asuspension of an implicit TWT schedule or a resumption of the implicitTWT schedule after the implicit TWT schedule has been suspended. Forexample, referring to FIG. 3, the AP 302 may receive a TWT informationmessage from the STA 306. The TWT information message may indicate thatthe STA 306 wants to suspend the implicit TWT schedule. In anotherexample, if the implicit TWT schedule has already been suspended, the AP302 may receive a TWT information message from the STA 306 indicating arequest to resume the implicit TWT schedule.

Although the aforementioned examples describe an AP as an apparatusperforming the steps in the method 500, a STA may also perform the stepsof the method 500. That is, the AP may be the TWT requester and the STAmay be the TWT responder. In another aspect, STAs may be engaging indevice-to-device communications, and one STA may be the TWT requesterand another STA may be the TWT responder.

Broadcast TWT Scheduling

FIG. 6 is an exemplary diagram 600 of a wireless network implementingbroadcast TWT scheduling and an exemplary timing flow diagram 650 forTWT operation. The diagram illustrates an AP 602 broadcasting ortransmitting within a BSA 604. STAs 606, 608, 610 are within the BSA 604and are served by the AP 602. The STAs 606, 608, 610 and the AP 602 mayperform non-negotiable TWT scheduling. In an aspect, wireless devicesmay optionally negotiate TBTTs during TWT setup.

In broadcast TWT scheduling, the delivery of TWT schedules may occurwithout a negotiation between devices. The AP 602 may determine 612 aTWT schedule for communicating with one or more STAs. The AP 602 maydetermine the TWT schedule by determining that the AP 602 has data totransmit to the STAs (e.g., buffer approaching capacity or bufferedunits available for delivery), that the STAs 606, 608, 610 have data totransmit to the AP 602, and/or that an access medium is available. Basedon such buffer status and network conditions, the AP 602 may scheduleone or more wake up times for the STAs 606, 608, 610 after which the AP602 may transmit trigger frames to enable communication. The AP 602 mayindicate an intention to transmit one or more trigger frames in a firstmessage 614 (e.g., a beacon frame transmitted at or after a scheduledTBTT (in an aspect, the TBTT may be negotiated between wireless devices)or a management message intended for one or more STAs) that is receivedby the STAs 606, 608, 610 at a given instant of time. The TBTT maycorrespond to the time when a beacon carrying the TWT element containinga broadcast TWT is scheduled to be delivered. The first message 614 mayinclude a TWT element (e.g., the TWT element 200 illustrated in FIG. 2).The first message 614 may include a first element ID identifying the TWTelement 200 and one or more TWT parameter sets as described below (see,for example, FIG. 16). In the description below, details are provided tothe signaling contained in one of these TWT parameter sets. The firstmessage 614 may include a first TWT request field having a value of 0 toindicate that the TWT element is not a request (a TWT request field witha value of 0 indicates that the TWT element is a response or is notrequest). The first message 614 may indicate one or more scheduled TWTs(either explicitly or implicitly, as discussed above) that indicate whenSTAs should wake up. The one or more scheduled TWTs may not be part of aTWT negotiation; that is, the STAs 606, 608, 610, upon receiving thefirst message 614, may not be able to negotiate for a differentscheduled TWT. Further, the STAs 606, 608, 610 may also not be able tonegotiate other parameters within the TWT element. The one or morescheduled TWTs may be included in the TWT field(s) or other field(s)within the TWT element. The first message 614 may include a firsttrigger field with a value of 1 to indicate that one or more triggerframes will be sent during one or more TWT service periods associatedwith the one or more scheduled TWTs. In other words, the first message614 may indicate to STAs that during the TWT service period 1, the STAsmay have a scheduled TWT and a trigger frame may be sent at thescheduled TWT. The first message 614 may further indicate that othertrigger frames may be sent during subsequent TWT service periods (e.g.,TWT service period 2). The first message 614 may include a broadcastindicator/subfield), which may be a bit that is included in the controlfield or some other field within the TWT element. In one aspect, thebroadcast indicator may be set to 1 to indicate the first message 614includes a TWT element with non-negotiable parameters (e.g., the TWTelement is a broadcast TWT element). In another aspect, the broadcastindicator may be set to 0 to indicate the first message 614 includes aTWT element with negotiable parameters, in which case the TWT elementmay be associated with a solicit TWT as discussed above. In anotheraspect, the broadcast indicator may be based on a value of the TWT setupcommand subfield of the request type field. For example, when the TWTsetup command subfield is set to a certain value which is any value lessthan 3, and the TWT request field is set to 0, then the first message614 is a non-negotiable TWT scheduling message.

When a TWT element is transmitted in the first message 614, the firstmessage 614 may include any one of the fields in the TWT element (e.g.,the TWT element 200 in FIG. 2). The TWT element may include multiplegroups of fields (or TWT parameter sets), and each group of fields (orTWT parameter) may correspond to a single given scheduled TWT. Forexample, a TWT element may include multiple scheduled TWTs, and each TWTmay be associated with a separate group of TWT fields (e.g., requesttype, target wake time, TWT group assignment field, etc.) as depicted inFIG. 16. In another aspect, instead of having two or more groups offields within a single TWT element when multiple TWTs are transmittedwithin the first message 614, the AP 602 may include multiple TWTelements within the first message 614, and each TWT element may includeone TWT and an associated group of TWT fields.

Referring to FIG. 2, the target wake time field may be 8 octets or less.In an aspect, when the AP 602 broadcasts the TWT element in the firstmessage 614, the AP 602 may determine to use less than 8 octets toindicate the scheduled TWT to save space. In an aspect, assuming the AP602 and the STAs 606, 608, 610 are already time synchronized (e.g., thebeacon carrying the TWT element already carries the TSF timer in thetimestamp field), the TWT field may indicate the least significantoctets of the binary value that the timing synchronization function(TSF) timer will have at the scheduled TWT. For example, the TWT fieldmay use the 3 least significant bytes to indicate the scheduled TWT. Inanother aspect, the TWT field may include even less bits if the AP 602wants to provide less resolution for the TWT (e.g., 10 μs rather than 1μs which would be the resolution of a generic TSF timer for wirelessdevices). In yet another aspect, the TWT field may be used to indicatean estimated time at which the trigger frame may be sent or an estimatedtime for the scheduled TWT relative to the end of the first message 614.For example, if the TWT field has a value of 100 ms, that may indicateto the STAs 606, 608, 610 to wake up 100 ms after the last field of thefirst message 614 is received, or may indicate to the STAs 606, 608, 610that the trigger frame may be received by the STAs 606, 608, 610approximately 100 ms after the STAs 606, 608, 610 received the entiretyof first message 614. In yet another aspect, the subset of bits in theTWT field may be a shifted subset of the bits corresponding to the TSFtimer. For example, assuming the TSF timer has 8 bytes. Instead ofincluding the least significant 3 bytes, the subset may be shifted inwhich the TWT field includes the second, third, and fourth leastsignificant bytes of the 8 byte representation of the TSF timer. Incertain embodiments, the bit shifting may occur at the bit level ratherthan the byte level.

In another aspect, when the TWT element is included in the first message614, the TWT wake interval may be valid only for the beacon intervalthat follows the first message 614 that is sent at the beginning of thebeacon interval. In another aspect, the TWT wake interval may be validfor the delivery traffic indication map (DTIM) interval if the firstmessage 614 that includes the TWT element is a DTIM beacon. In anotheraspect, the TWT wake interval may be valid for the duration of theexistence of the basic service set. That is, the TWT wake interval maybe valid so long as the STA remains associated with the AP.

In another aspect, the TWT element may include a flow identifier (e.g.,one or more of the TWT flow identifier fields in the requests field oranother field in the groups of fields of the TWT element) that indicatesone or more types of allowed data flows. In one configuration, if theTWT flow identifier may have a value of 0, then the trigger frameassociated with the first message 614 may be for wild card (or random)access from unassociated STAs. If an unassociated STA wants to send anassociation request or a probe request to the AP 602, for example,unassociated STAs may wake up at the scheduled TWT indicated in thefirst message 614 and randomly select a subchannel/subband to transmitthe association request/probe request using on a random back off oranother collision avoidance mechanism. If the TWT flow identifier has avalue of 1, then the trigger frame associated with the first message 614may be for wild card access from associated STAs. For example, if theSTA 606 receives the first message 614 in a broadcast, the STA 606 maydetermine to wake up at the one or more scheduled TWTs indicated in thefirst message 614. The STA 606 may receive one or more trigger messagesat the one or more scheduled TWTs and transmit uplink data to the AP 602after receiving the one or more trigger messages. If the TWT flowidentifier has a value of 2, associated STAs in power save mode maytransmit upon receiving the trigger frame at the scheduled TWT. If theTWT flow identifier has a value of 3, associated STAs may transmit voicetraffic upon receiving the trigger frame at the scheduled TWT. If theTWT flow identifier has a value of 4, associated STAs may transmit videotraffic upon receiving the trigger frame at the scheduled TWT.

In another configuration, the types of allowed data indicated by the TWTflow identifier may include: multi-user OFDMA random access forunassociated STAs, multi-user OFDMA random access for associated STAs,multi-user downlink OFDMA scheduled access for TIM STAs, multi-useruplink OFDMA scheduled access for TIM STAs, multi-user uplink MIMOscheduled access for TIM STAs, and/or multi-user downlink MIMO scheduledaccess for TIM STAs.

In the first category, multi-user OFDMA random access for unassociatedSTAs, only unassociated STAs may transmit data to the AP 602 followingthe reception of the trigger frame sent at the one or more scheduledTWTs during the TWT service periods by the AP 602. The frames that canbe sent by the unassociated STAs may include a probe request, anassociation request, a reassociation request, an authentication request,etc. The frames may be sent in any OFDMA resource following a randomaccess procedure for selecting the OFDMA resource for transmission.Regarding the random access procedure, one or more unassociated STAs mayrandomly select an OFDMA channel for transmitting the frames. Theunassociated STAs may coordinate with each other such that if two ormore unassociated STAs randomly select the same OFDMA channel, theunassociated STAs will randomly select another OFDMA channel until eachunassociated STA has selected a different OFDMA channel.

In the second category, multi-user OFDMA random access for associatedSTAs, only associated STAs (STAs 606, 608, 610) may transmit followingthe reception of a trigger frame sent by the AP 602 during a TWT serviceperiod associated with the one or more scheduled TWTs. The frames thatcan be sent by the associated STAs may be any frame. The frames may bePS-Poll or APSD trigger frames, or any other frame that can be used toindicate to the AP 602 that the buffer status and/or transmissionpreferences of the associated STAs. Transmission preferences may includea preferred MCS, bandwidth, subchannel, etc.

In the third category, multi-user downlink OFDMA scheduled access forTIM STAs, only STAs for which an association identifier (AID)corresponds to a value of 1 in a traffic information map (TIM) elementbitmap included in a beacon message (e.g., the first message 614)carrying the TWT element may receive data from the AP 602 afterreceiving the trigger frame that is sent at the scheduled TWT or duringthe TWT service period. In certain embodiments, instead of transmittinga trigger frame, the AP 602 may transmit downlink data to the STAs inmulti-user OFDMA. The AP 602 may also indicate in the trigger frameuplink OFDMA resources associated with each STA to be used within thesame scheduled TWT or TWT service period.

In the fourth category, multi-user uplink OFDMA scheduled access for TIMSTAs, only STAs for which an AID corresponds to a value of 1 in the TIMelement bitmap included in a beacon message (e.g., the first message614) carrying the TWT element may transmit data after receiving thetrigger frame that is sent at the scheduled TWT during the TWT serviceperiod. The AP 602 may indicate that the TWT service period is allocatedfor uplink transmission only. The AP 602 may decide to transmit downlinkdata to the STAs after terminating the first trigger-enabled exchange.

In the fifth and sixth categories, multi-user uplink MIMO scheduledaccess for TIM STAs and multi-user downlink MIMO scheduled access forTIM STAs, APs and STAs whose AID bit is 1 in the TIM element mayexchange downlink and uplink data using multi-user MIMO. As previouslyindicated other fields, not just the TWT flow identifier field, mayindicate the allowed data categories. For example, the TWT wake intervalexponent subfield may be overloaded to signal the allowed data typesinstead of the TWT flow identifier field.

In another aspect, a flow identifier may be used to indicate a trafficclass or traffic identifier (TID) that identifies a type of trafficallowed to be exchanged during the TWT service period. For example, asdiscussed previously, the flow identifier may be used to indicate thetypes of flows that may be allowed in response to a trigger frame. Thetraffic type may include voice and video traffic.

When the STA 606 receives the first message 614, the STA 606 maydetermine whether to be awake during the one or more TWT service periodsassociated with the one or more scheduled TWTs included in the firstmessage 614. The STA 606 may determine whether to be awake during theone or more TWT service periods by determining whether the STA 606 hasdata to transmit to the AP 602 and by determining whether the STA 606expects to receive data from the AP 602.

During a TWT service period associated with the scheduled TWT includedin the first message 614 in which a trigger frame is expected, the STAs606, 608, 610 may not contend for access to the medium for datatransmission. Instead, the STAs 606, 608, 610 may wait to receive atrigger frame 616 sent by the AP 602 that enables the STAs 606, 608, 610to transmit data frames. The data frames may be sent in either singleuser or multi-user mode.

Assuming the STA 606 determines to participate in TWT scheduling, uponreceiving the trigger frame 616, the STA 606 may transmit data 618 to orreceive data 618 from the AP 602. The data 618 may be transmitted duringthe TWT service periods. STAs (e.g., the STA 606) that fail to transmitafter the trigger frame 616 may transmit after the TWT service periodends. The transmission may be a retransmission of a failed transmissionor it may be a resource allocation request.

FIG. 7 is a flowchart of an example method 700 of broadcast TWTscheduling. The method 700 may be performed using an apparatus (e.g.,the AP 602, the STA 606, or the wireless device 1302, infra, forexample). Although the method 700 is described below with respect to theelements of wireless device 1302 of FIG. 13, infra, other components maybe used to implement one or more of the steps described herein.

At block 705, the apparatus may determine a TWT schedule for otherwireless devices. The apparatus may determine the TWT schedule bydetermining one or more fields within the TWT element. In an aspect, theapparatus may determine network conditions (e.g., a number of wirelessdevices expected to communicate with the apparatus and/or an amount oftraffic on the wireless medium). For example, referring to FIG. 6, theAP 602 may determine a broadcast TWT schedule for one or more STAs. Thebroadcast schedule may include non-negotiable TWT parameters forcommunicating with the AP 602. The AP 602 may determine the broadcastTWT schedule by determining whether to utilize an implicit TWT scheduleor an explicit TWT schedule. Further, the one or more TWTs associatedwith the broadcast TWT schedule. The AP 602 may determine any of theother fields or parameters associated with the TWT element (e.g., theTWT element 200).

At block 710, the apparatus may broadcast a message that includes theTWT schedule to a plurality of wireless devices. The message may includea broadcast indicator that indicates the TWT schedule is a broadcast TWTschedule. In an aspect, the message may include a trigger field thatindicates whether the apparatus will transmit a trigger message at astart of or during a TWT service period. The message may further includea TWT flow identifier that indicates a type of data flow allowed duringthe TWT service period. For example, referring to FIG. 6, apparatus maybe the AP 602. The AP 602 may broadcast the first message 614 thatincludes a TWT schedule. The broadcast bit in the first message 614 maybe set to 1, indicating that the TWT schedule is a broadcast TWT. Thefirst message 614 may also include a trigger field set to 1, indicatingthat the AP 602 will transmit a trigger frame during the TWT serviceperiod. The first message 614 may include an implicit field set to 0,indicating that the TWT schedule is an explicit TWT schedule. The firstmessage 614 may further include 4 scheduled TWTs associated with 4 TWTparameter sets. In an aspect, the first message 614 may include arepetition indicator that indicates that the TWT schedule is valid for 5TWT service periods. In another aspect, the first message 614 mayinclude a TWT protection indicator set to 1, indicating that messagesexchanged between the STA 606 and the AP 602 are to be preceded by a RTSmessage from the transmitter and a CTS message from the receiver.

At block 715, the apparatus may transmit a trigger message based on theTWT schedule. The trigger message may include a cascaded indicator thatindicates whether the apparatus will transmit additional triggermessages in a TWT service period. For example, referring to FIG. 6, theAP 602 may transmit the trigger frame 616. In an aspect, for MUoperation, the AP 602 may transmit multiple trigger frames within a TWTservice period to enable multiple STAs to transmit to the AP 602. Assuch, the AP 602 may transmit the trigger frame 616 addressed to STAs606, 608 with a cascaded indicator set to 1 to indicate that the AP 302will transmit another trigger frame within the same TWT service period.The STAs 606, 608 may transmit uplink data to the AP 602 based on thetrigger frame 616. Subsequently, the AP 602 may transmit another triggerframe addressed to the STAs 608, 610 to indicate resources for anotheruplink transmission.

At 720, the apparatus may transmit a TWT information message to thesecond wireless device. The TWT information message may indicate asuspension of the implicit TWT schedule or a resumption of the implicitTWT schedule after the implicit TWT schedule has been suspended. Forexample, referring to FIG. 6, the AP 602 may transmit a TWT informationmessage to the STAs 606, 608, 610 indicating a suspension of thebroadcast TWT schedule indicated in the first message 614 if thebroadcast TWT schedule is an implicit TWT schedule. In an aspect, theimplicit TWT schedule may be suspended based on network conditions, lackof data for transmission, or to conserve power. In another aspect, toresume a previously suspended implicit TWT schedule, the AP 602 maytransmit a TWT information message to the STAs 606, 608, 610 indicatinga resumption of a suspended TWT schedule.

At block 725, the apparatus may transmit a TWT information message tothe second wireless device. The TWT information message may indicate adifferent scheduled TWT than in the broadcasted message. For example,referring to FIG. 6, the AP 602 may transmit a TWT information messageto the STAs 606, 608, 610 that indicates a different scheduled TWT thanwhat has been implied in the implicit TWT schedule. In another example,if the TWT schedule is an explicit TWT schedule, then the TWTinformation message may include a different scheduled TWT than the TWTsindicated in the explicit TWT schedule in the first message 614.

Although the aforementioned example provides that an AP broadcasts a TWTschedule, the STA may broadcast a TWT schedule to an AP or to anotherSTA.

FIG. 8 is a flowchart of an example method 800 of communicating based onbroadcast TWT scheduling. The method 500 may be performed using anapparatus (e.g., the STA 606, or the wireless device 1302, infra, forexample). Although the method 800 is described below with respect to theelements of wireless device 1302 of FIG. 13, infra, other components maybe used to implement one or more of the steps described herein.

At block 805, the apparatus may receive from a second wireless device amessage that includes a TWT schedule. The message may include abroadcast indicator that indicates the TWT schedule is a broadcast TWTschedule. For example, referring to FIG. 6, the apparatus may be the STA606. The STA 606 may receive from the AP 602 the first message 614 thatinclude a TWT schedule. The first message 614 may include a broadcastindicator set to 1, indicating that the TWT schedule is a broadcastschedule. The first message 614 may include a trigger field set to 1,indicating that the AP 602 will transmit the trigger frame 616 at thestart of or during the TWT service period. The first message 614 mayfurther include a TWT flow identifier set to 1, indicating that thereare no constraints on the types of frames or messages during thebroadcast TWT service period.

At block 810, the apparatus may determine one or more TWTs for theapparatus based on the TWT schedule. The apparatus may determine one ormore TWTs by determining if the TWT schedule is an implicit or explicitTWT schedule. If the TWT schedule is an implicit TWT schedule, then theapparatus may determine one or more TWTs based on the first TWTindicated in the TWT schedule. Subsequent TWT may be determined based onthe TWT wake interval mantissa and on the wake interval exponent, whichmay be indicated in the message or preconfigured at the apparatus. Ifthe TWT schedule is an explicit TWT schedule, then the apparatus mayextract the one or more TWTs from the received message. For example,referring to FIG. 6, the STA 606 may determine whether the TWT scheduleindicated in the first message 614 in an implicit or explicit TWTschedule, and either calculate or extract the TWT values based on thedetermination.

At block 815, the apparatus may receive a trigger message based on thedetermined one or more TWTs. For example, referring to FIG. 6, the STA606 may receive the trigger frame 616 based on the determined one ormore TWTs.

At block 820, the apparatus may determine to transmit to the secondwireless device during a TWT service period when the trigger message isreceived from the second wireless device. For example, referring to FIG.6, the STA 606 may determine to transmit to the AP 602 by determiningthat data is available for transmission to the AP 602, by determiningthat the data may be transmitted during the TWT service period, and bydetermining that the trigger frame 616 has been received from the AP602.

At block 825, the apparatus may determine to transmit to the secondwireless device outside of the TWT service period based on EDCAparameters associated with AC_BE or AC_BK. For example, referring toFIG. 6, the STA 606 may determine that data is available fortransmission to the AP 602, and either no trigger frame has beenreceived from the AP 602 or the data cannot wait for the next availableTWT service period. As such, the STA 606 may determine to transmit tothe AP 602 by contending for medium access based on a lower priorityEDCA access category, AC_BE.

At block 830, the apparatus may receive a TWT information message fromthe second wireless device. The TWT information message may indicate asuspension of the implicit TWT schedule or a resumption of the implicitTWT schedule after the implicit TWT schedule has been suspended. Forexample, referring to FIG. 6, the STA 606 may receive a TWT informationmessage from the AP 602, indicating a suspension of the implicit TWTschedule or a resumption of the suspended, implicit TWT schedule.

At block 835, the apparatus may receive a TWT information message fromthe second wireless device. The TWT information message may indicate adifferent scheduled TWT than in the received message. For example,referring to FIG. 6, the STA 606 may receive a TWT information messagefrom the AP 602, and the TWT information message may indicating adifferent scheduled TWT than the TWT indicated in the first message 614.

TWT Power Save Mode

In future IEEE 802.11 standards, an AP may send trigger frames tosolicit uplink data frames from and/or transmit downlink data frames toone or more STAs in multi-user mode. In general, trigger frames may begenerated by the AP any time. A STA that intends to transmit uplink datamay have to stay awake to receive the trigger frame intended for theSTA. However, staying awake during periods when no trigger frame will besent may lead to unnecessary power consumption as the AP can scheduledmultiple trigger frames for multiple STAs. One way to resolve this issueis to allow the STA and the AP to negotiate target trigger transmittimes, as discussed previously, so that the STA knows when the triggerframe(s) will arrive. These transmit times may be negotiated (solicitTWT or unsolicit TWT) to be periodic or aperiodic or may not benon-negotiated (broadcast TWT).

In certain instances, the scheduled TWTs may dynamically change betweena periodic pattern to an aperiodic pattern based on a pattern indicationby either the AP or the STA. The pattern indication may be indicated byan implicit field that is contained in the message carrying the triggerfield. The implicit field may be set to 1 to indicate that the patternis periodic and may be set to 0 to indicate that the pattern isaperiodic.

When the pattern is aperiodic, the next TWT may be explicitly signaledby a TWT responder (e.g., an AP). In an aspect, the TWT responder maytransmit a TACK/STACK/BAT or TWT information frames to signal the nextTWT. These frames may contain the value of the next TWT and the TWT flowidentifier that identifies the TWT flow to which the next TWTcorresponds to in the case of a solicit TWT agreement. The TWT requestermay request a change of pattern for the next TWT by sending aTACK/STACK/BAT frame that carries a next TWT field. The TWT requestermay confirm the new schedule in a successive frame that contains a NextTWT field (TACK/STACK/BAT etc).

When the pattern is periodic the TWT responder does not provide the nextTWT during a current TWT service period. Instead the TWT requesterimplicitly calculates the next TWT every TWT service period based on thevalue of the TWT at the current TWT service period plus the value of thenegotiated TWT wake interval as specified in the negotiation period ofthe TWT. During a periodic TWT (i.e., implicit TWT) either of thedevices may request a rescheduling of the parameters for a given TWTflow. This may be performed by sending a request or response withupdated parameters anytime during a TWT service period. The request orresponse in this case may have a dialog token that is equal to thedialog token value exchanged during the TWT setup. Similarly, therequest or response may contain the TWT Flow Identifier for which therescheduling is requested. The request may be confirmed, an alternativemay be provided, or the request may be refused. In certain embodiments aresponse to re-negotiate the parameters may be non-negotiable and totake effect starting from the next TWT.

In certain cases, even though the AP and the STA may have an agreement(e.g., a schedule) for exchanging uplink/downlink frames following thetrigger frame in a periodic pattern (e.g., during the TWT serviceperiods), there may be periods of time where one of the STAs does notexpect traffic for a long period of time. As such, a need exists toenable to STA to indicate a suspension of the agreed upon schedule for agiven amount of time. This way, the STA does not need to wake up duringcertain TWT service periods at which the STA has no uplink data totransmit to the AP. Also in certain cases, the AP does not plan to usethe full TWT service period for sending trigger frames, and, as such,the AP may want to indicate an early termination of a given TWT serviceperiod.

FIG. 9 is an exemplary diagram 900 of a wireless network supportingpower save modes for TWT scheduling and an exemplary timing flow diagram950 for TWT operation. The diagram illustrates an AP 902 broadcasting ortransmitting within a BSA 904. STAs 906, 908, 910 are within the BSA 904and are served by the AP 902.

In one configuration, the STA 906 (or any other STA) may be in one oftwo different power states: an awake state and a doze (or sleep) state.In the awake state, the STA is fully powered. In the doze state, the STA906 may not able to transmit or receive data and may consume very littlepower. The STA 906 may transition between the awake state and the dozestate based on power management modes—active mode (AM) and power save(PS) mode. In the active mode, the STA 906 may be in a continually awakestate. In the PS mode, the STA 906 is in a doze state and may enter theawake state to receive selected beacons, to receive group addressedtransmissions following certain received beacon frames, to receivetransmissions during the service period of a scheduled groupcast withretries service period (GCR-SP), to transmit, or to wait for responsesto transmitted PS-poll frames or to receive contention free (CF)transmission of data.

To change power management modes, the STA 906 may inform the AP 902through a successful frame exchange that is initiated by the STA 906.The frame may be a management, extension, or data frame and may includean acknowledgment (ACK) or a BlockACK frame from the AP 902. The framemay include a power management subfield(s) in the frame control field,and the power management subfield may indicate the power management modethat the STA 906 may adopt upon successful completion of the entireframe exchange (e.g., frame and acknowledgment). The STA 906 may notchange power management mode using a frame exchange that does notreceive an ACK or a BlockACK frame from the AP 902, or using aBlockACKReq frame. When the AP 902 receives the frame from the STA 906indicating a mode change, the AP 902 may store the new power managementmode and transmit the ACK frame to the STA 906.

If the STA 906 has negotiated TWTs with the AP 902, the STA 906 may bein active mode at each scheduled TWT and for a certain period after that(e.g., during the TWT service periods associated with the scheduledTWTs), even though the STA 906 has no uplink data to transmit. This maybe a burden for the STA 906 that has no more data to transmit to the AP902. In an aspect, the STA 906 may use a TWT power save mode to conservepower.

In the TWT power save mode, the STA 906 may be in a doze state and mayenter an awake state at the start of the scheduled TWT and may remain inthe awake state for the duration of one or more TWT service periodsassociated with the scheduled TWT. In another aspect, the STA 906 mayremain awake for a minimum time duration that is less than the TWTservice period. During times outside of the TWT service periods,however, the STA 906 may enter a doze state. In the TWT power save mode,if there are additional TWT service periods associated with thescheduled TWT and the STA 906 has no more data left to transmit (and/ordoes not expect to receive any data from the AP 902), the STA 906 maywant to enter the sleep state for the remaining TWT service periods(e.g., switch to power save mode). For this case, a power save moveswitch signaling is needed as described below. In one configuration,when the STA 906 is in the TWT power save mode, the STA 906 mayadditionally continue to satisfy the requirements of the existing PSmode (e.g., enter the awake state to receive selected beacons, toreceive group addressed transmissions following certain received beaconframes, to receive transmission during the service period of a scheduledgroupcast with retries service period (GCR-SP), to transmit, or to waitfor responses to transmitted PS-poll frames or to receive contentionfree (CF) transmission of data.) In another configuration, the STA 906may not satisfy the requirements of the PS mode and simply remain in asleep state.

Referring to FIG. 9, when the STA 906 determines 912 to switch to a TWTpower save mode, the STA 906 may transmit a message 914 (e.g., a frame)to the AP 902 indicating that the STA 906 intends to switch from anactive mode to a TWT power save mode or from a PS mode to a TWT powersave mode. The message 914 may include an indicator or field (e.g., anend of service period (EOSP) field) that indicates the power managementmode that the STA 906 will adopt upon successful completion of themessage/frame exchange. For example, if the field is set to 1 (e.g.,EOSP is 1), then the message 914 may indicate that the STA 906 isswitching from a TWT power save mode to PS mode. If the field is set to0, then the message 914 indicates that the STA 906 is not switching fromthe TWT power save mode to the PS mode. In certain embodiments, anyfield in a frame exchanged with the AP 902 can signal this new state. Inother embodiments, certain frame types may be used to signal thetransition to or from the TWT power save mode. In an aspect, the STA 906may only switch between the active mode and the TWT power save mode, oronly between the PS mode and the TWT power save mode. In this aspect,the transition between states may be signaled by a 1-bit powermanagement subfield in the message 914. When the power managementsubfield has 1 bit, the STA 906 may be able to switch between twomodes—active mode and TWT power save mode or TWT power save mode and PSmode. In another aspect, the power management subfield may have 2 bits,which would enable the STA 906 to switch between all three modes. Forexample “00” could represent the PS mode, “01” could represent the TWTPS mode, and “10” could represent the active mode.

Upon receiving the message 914, the AP 902 may store the powermanagement mode to which the STA 906 intends switch. For example, if themessage 914 indicates that the STA 906 intends to switch to the TWTpower save mode, then the AP 902 may store information indicating thatthe STA 906 is in a TWT power save mode. In this mode, the AP 902 mayknow not to transmit any data to the STA 906 outside of the TWT serviceperiods in which the STA 906 is awake. Subsequently, the AP 902 maytransmit an acknowledgment message 916 to the STA 906 indicating thatthe AP 902 received the message 914.

In an aspect, the AP 902 may transmit a second message 918 to the STA906. The second message 918 may instruct the STA 906 to switch from aTWT power save mode to a PS mode using an EOSP field. For example, theAP 902 may set the EOSP field to 1 to instruct the STA 906 to switchfrom the TWT power save mode to the PS mode. The AP 902 may alsotransmit the second message 918 to other STAs 908, 910.

Once the STA 906 goes into PS mode, however, the AP 902 may not be ableto indicate to the STA 906 to switch back to the TWT power save mode bysending a frame that is intended to indicate to the STA 906 to switchmodes because the STA 906 may be in a sleep state for an extended periodof time. However, the STA 906 may request to switch back to the TWTpower save mode by sending a request to switch (e.g., a request similarto the message 914). For example, the STA 906 may transmit anothermessage to the AP 902. The other message may include an EOSP field setto 0 to indicate that the STA 906 requests to switch back to the TWTpower save mode. Otherwise, the STA 906 may set the EOSP to 1 toindicate that the STA 906 does not want to switch back to the TWT powersave mode. In certain embodiments, the power management subfield may beused for similar signaling. In certain embodiments, the power managementswitch may be performed by sending a TWT request or an unsolicited TWTresponse. In certain embodiments, the AP 902 may selectively indicate tocertain STAs to switch from PS mode to TWT power save mode by activatinga bit in a traffic indication map element that may be included in amessage frame (e.g., the second message 918). For example, the secondmessage 918 may be a beacon message, and the second message 918 mayinclude a TIM element that includes a bitmap. The STAs 906, 908, 910 mayreceive the second message 918 and determine whether to switch to a TWTpower save mode based on the each AID position in the bitmap. Forexample, if a position in the bitmap corresponding to the AID of the STA906 has a value of 0, then the STA 906 may switch to the TWT power savemode. In certain embodiments, the validity of the new mode is limited tothe beacon interval that follows the beacon frame (e.g., the secondmessage 918).

FIG. 10 is a flowchart of an example method 1000 of switching to or froma TWT power save mode. The method 1000 may be performed using anapparatus (e.g., the STA 906, the AP, 902, or the wireless device 1302,infra, for example). Although the method 1000 is described below withrespect to the elements of wireless device 1302 of FIG. 13, infra, othercomponents may be used to implement one or more of the steps describedherein.

At block 1005, the apparatus may receive an indication from the secondwireless device instructing the apparatus to switch to or to switch awayfrom the TWT power save mode. For example, referring to FIG. 9, theapparatus may be the STA 906, and the STA 906 may receive a message fromthe AP 902 instructing the STA 906 to switch to the TWT power save mode.In an aspect, the message may include an EOSP set to 1, indicating thatthe TWT service period is ending and no more data will be transmitted.

At block 1010, the apparatus may determine whether to switch to anactive mode, a power save mode, or a TWT power save mode. In the TWTpower save mode, the apparatus may enter an awake state during TWTservice periods and enter a doze state outside of the TWT serviceperiods. In one configuration, the apparatus may determine whether toswitch by determining if there is additional data for transmission orreception by the apparatus. In another configuration, the apparatus maydetermine whether to switch modes by receiving a QoS message from thesecond wireless device and by determining whether the QoS messageincludes an EOSP indicator set to 0 or 1. In another configuration, theapparatus may determine whether to switch modes by receiving a triggermessage from the second wireless device and by determining whether thetrigger message includes a cascaded indicator set to 0 or 1 and bydetermining whether the trigger message is intended for the apparatus.For example, referring to FIG. 9, the STA 906 may determine to switch tothe TWT power save mode based on the determination that a QoS message isreceived from the AP 902 indicating an EOSP set to 1.

At block 1015, the apparatus may transmit a message to a second wirelessdevice based on the determination. For example, referring to FIG. 9, theSTA 906 may transmit the message 914 to the AP 902 based on thedetermination to switch to the TWT power save mode. The message 914 mayinclude a power management field set to 1, indicating that the STA 906wants to switch to the TWT power save mode.

At block 1020, the apparatus may determine a mode of the second wirelessdevice. In one configuration, the apparatus may determine the mode byreceiving a second message from the second wireless device that includesa responder mode indicator. The apparatus may determine whether theresponder mode indicator indicates whether the second wireless device isin the doze state outside of the TWT service periods. If so, then thesecond wireless device may be in the TWT power save mode; otherwise, thesecond wireless device may be in the active mode. In anotherconfiguration, the apparatus may determine the mode by receiving atrigger message from the second wireless device and by determiningwhether the trigger message includes resource allocations to anywireless devices. For example, referring to FIG. 9, the STA 906 mayreceive a message from the AP 902 that includes a responder PM modeindicator (e.g., in a control field). The responder PM mode indicatormay be set to 1, indicating that the AP 902 is in the TWT power savemode.

At block 1025, the apparatus may receive from the second wireless devicea second message that includes a traffic indication map. The trafficindication map may indicate a mode of operation for the first wirelessdevice to select. For example, the STA 906 may receive from the AP 902message that includes a TIM. The TIM may include a bit associated withthe AID of the STA 906. If the bit is set to 1, then the STA 906 mayexpect to receive data and may enter into a TWT power save mode or anactive mode, but if the bit is set to 0, then the STA 906 may not expectto receive data and may enter into a power save mode.

FIG. 11 is a flowchart of an example method 1100 of signaling forswitching to a TWT power save mode. The method 1100 may be performedusing an apparatus (e.g., the AP 902, STA 906, or the wireless device1302, infra, for example). Although the method 1100 is described belowwith respect to the elements of wireless device 1302 of FIG. 13, infra,other components may be used to implement one or more of the stepsdescribed herein.

At block 1105, the apparatus may receive a message from a secondwireless device that indicates an intention of the second wirelessdevice to switch to an operating mode that is one of an active mode, apower save mode, or a TWT power save mode. During the TWT power savemode, the second wireless device may enter an awake state during TWTservice periods and enter a doze state outside of the TWT serviceperiods. For example, referring to FIG. 9, the apparatus may be the AP902. The AP 902 may receive the message 914 from the STA 906 indicatingan intention of the STA 906 to switch to a TWT power save mode duringwhich the STA 906 may enter an awake state during TWT service periodsand may enter a doze state outside of the TWT service periods.

At block 1110, the apparatus may store the operating mode associatedwith the second wireless device. For example, referring to FIG. 9, theAP 902 may store information indicating that the STA 906 is in the TWTpower save mode.

At block 1115, the apparatus may transmit to the second wireless devicean acknowledgment of the operating mode switch. For example, referringto FIG. 9, the AP 902 may transmit the acknowledgment message 916indicating that the AP 902 acknowledges the switch to the TWT power savemode by the STA 906.

At 1120, the apparatus may transmit a QoS message that includes an EOSPindicator set to 1 to instruct the second wireless device to switchoperating modes. For example, referring to FIG. 9, the AP 902 maytransmit a QoS frame to the STA 906 with an EOSP indicator set to 1,which instructs the STA 906 to switch operating modes.

At 1125, the apparatus may transmit a responder mode indicator thatindicates whether the first wireless device is in a doze state outsideof the TWT service periods. For example, referring to FIG. 9, the AP 902may transmit a message that includes the responder PM mode indicator ina control field, and the responder PM mode indicator may be set to 1,indicating that the AP 902 is in TWT power save mode.

At 1130, the apparatus may transmit a trigger message with unassignedresources to indicate that the apparatus will enter into a doze state.For example, referring to FIG. 9, the AP 902 may transmit a triggerframe with unassigned resources to the STAs, which indicates that the AP902 will enter into a doze state.

At 1135, the apparatus may transmit a traffic indication map thatindicates the operating mode for the second wireless device to select.For example, referring to FIG. 9, the AP 902 may transmit the TIM with abit set to 1 corresponding to the AID of the STA 906, which indicatesthat the STA 906 should be in the active mode.

At 1140, the apparatus may transmit an indication to the second wirelessdevice instructing the second wireless device to switch to or to switchaway from the TWT power save mode. For example, referring to FIG. 9, theAP 902 may transmit the second message 918 instructing the STA 906 toswitch to a TWT power save mode from the active mode.

Additionally, during a TWT service period the AP may transmit one ormore trigger frames and/or may not want to always use the full durationof the TWT service period. For example the AP may want to send a triggerframe to poll one or more STAs for feedback (e.g., PS-polls or resourcerequests), a trigger frame for UL data delivery from the one or moreSTAs, a trigger frame to exchange DL data with one or more STAs, etc. Toallow the STAs determine the number of frames to expect or an earlytermination of the TWT service period the AP may indicate the number oftrigger frames the AP intends to transmit in the TWT element itself. Inanother embodiment, the AP may indicate that the AP has more triggerframes to transmit in any frame the AP transmits during the TWT serviceperiod. For example, the AP may indicate that the AP intends to transmitat least another trigger frame following the current frame by setting abit in the frame that is currently transmitting to 1. In one embodiment,the frame may be a trigger frame and the bit may be the More Data fieldin the Frame Control field, a newly defined field, or the AP may rely onthe EOSP field signaling. In another embodiment, the frame can be anyother frame sent by the AP. For example, the bit may be the powermanagement field in the frame control field of a frame transmitted bythe AP during the TWT service period. In another embodiment, any otherfield or value can be used for this purpose. For example an EOSP fieldcan be set to 1 to indicate that the AP does not intend to transmitanother (trigger) frame during this TWT service period. In anotherexample, the More Data field, or the other fields described above, maybe set to 0 to indicate that the AP intends to transmit another(trigger) frame during this TWT service period. Hence, STAs receivingthis indication (that there are no more trigger frames during this TWTservice period) may go to sleep earlier than the end of the scheduledTWT service period. The STAs that are addressed by the trigger frame maynot go to sleep as they are scheduled to transmit UL frames as aresponse to the trigger frame. The rest of the STAs that went to sleepfor the rest of the scheduled TWT service period may wake up in otherTWTs (next TWTs) as negotiated or indicated by the AP in previousexchanges or schedules.

FIG. 12 is an exemplary diagram of a request type field 1200 within aTWT element for broadcast TWT. Referring to FIG. 12, the request typefield may contain a TWT flow identifier subfield, which may have variousvalues as indicated in FIG. 12. The TWT flow identifier subfield maycontain a 3-bit value that identifies specific information associatedwith a TWT request uniquely from other requests made between a same TWTrequesting STA and a TWT responding STA pair. In broadcast TWT mode,there may not be a concept of a STA pair. As such, the TWT flowidentifier subfield may be used to specify different flows (or thetraffic class) that may be allowed for the broadcast TWT in a TWTservice period.

Referring to FIG. 12, in one aspect, when the TWT flow ID is set to 0,then there may not be any constraints on the type of frame that can beexchanged during the scheduled TWT service period(s) specified by theTWT parameter set of the broadcast TWT containing the TWT Flow ID. Inanother aspect, when the TWT flow ID is set to 1, then only frames thatcontain feedback and/or management information may be exchanged (e.g.,PS-Poll, CQI, buffer status, sounding information, action, etc.). Inthis aspect, the trigger frame may contain no RUs (e.g., resource units)for random access. In another aspect, when the TWT flow ID is set to 2,then only frames that contain feedback and/or management information maybe exchanged (e.g., PS-Poll, CQI, buffer status, sounding information,action, pre-association frames, etc.). In this aspect, the trigger framemay contain at least one RU (or resource unit) for random access. In anaspect, QoS frames may also be exchanged when the TWT flow ID is set to1 or 2. In yet another aspect, when the TWT flow ID is set to 3, qualityof service constrained frames (e.g., short frames with payloads lessthan 256 or 128 bytes of a particular AC/type, etc.) may be exchanged.

In another aspect, the TWT flow identifier subfield may indicate that notransmissions are expected from any device (e.g., APs or STAs that mayor may not be associated with the device transmitting the framecontaining the TWT element). For example, when the TWT flow ID is set to4 (or some other value), then no transmission are expected (i.e., ablack out service period). In addition to helping STAs conserve power,this feature may also be used to cause STAs to enter or remain in asleep mode in order to reserve a time duration for another device tocommunicate. This is beneficial also when the device transmitting thisTWT element is aware of other devices (not associated to it) that intendto transmit to one or more other devices during a scheduled period oftime (knowledge provided in some embodiments by the other devices viasimilar TWT elements or other means of schedule information exchangemechanisms).

Although the TWT flow ID values are provided in the TWT flow identifiersubfield, similar values for purposes of identifying a flow type for abroadcast TWT may be provided in other fields within a TWT element orother parts of frames transmitted by the device providing the schedulingfor one or more other devices.

FIG. 13 illustrates a method 1300 of broadcasting TWTs for multipleTWTs. Referring to FIG. 13, an AP may indicate a broadcast targettrigger (wake) time(s) in an information element (e.g., a TWT element)included in a beacon 1305 or in any other management frame. In oneaspect, the TWT pattern provided by the element may be periodic. As anexample, in this aspect, a TWT element may contain a TWT field and a TWTwake interval which enables the periodic pattern. In another aspect, thepattern may be aperiodic. In this aspect, a TWT element may signalmultiple aperiodic TWTs per beacon interval. This may allow for greaterflexibility of target wake times within a beacon interval, DTIMinterval, or through the lifetime of the operation.

To enable multiple aperiodic TWTs per beacon interval, etc, more thanone TWT parameter set may be included in a beacon frame or anotherframe. In one aspect, more than one TWT information element may beincluded in a beacon. In another aspect, a TWT element may be modifiedsuch that the TWT element may carry multiple TWT parameter sets. Forexample, the TWT element may carry multiple occurrences of the fieldsfollowing the control field of the element. The TWT parameter set mayconsist of one or more of the following fields: Request Type, TWT, TWTGrouping, Nominal Minimum Wake Duration, TWT Wake Interval Mantissa, TWTChannel, NDP Paging, etc. The length of the TWT elements may providesignaling to determine its content. As an example, if each TWT parameterset (which length is based on the signaling contained therein) is 7bytes, then the length field of the TWT element may be equal to 15 bytes(7*2 plus one byte of Control field) if the TWT element contains 2 TWTparameter sets, and so on.

FIG. 14 illustrates a method 1400 of employing a cascaded field (earliermentioned as more data, power management, etc.) in a trigger framewithin a TWT service period. Referring to FIG. 14, an AP may notify theSTAs expected to wake up at the TWT service period via an TWTinformation element included within a beacon 1405 or frame in general.In an aspect, the AP may overestimate a number of STAs to be allocatedin a TWT service period. This is because in broadcast TWT, only aportion of STAs may likely be served (or expected to be awake, or ableto successfully receive the frame carrying the TWT) during the TWTservice period (this is also possible for solicited TWTs (or negotiatedTWTs mentioned earlier)). As such, an AP may send a trigger frame 1410at the start of a TWT service period. The trigger frame 1410 may containa list of association identifiers (AIDs) (or other AP assignedidentifiers) for STAs to enable uplink transmission. That is, each AIDmay identify a STA. The trigger frame 1410 may contain a cascadedsubfield that indicates whether an additional trigger frame follows thetrigger frame 1410 in the TWT service period. For example, if thecascaded subfield is set to 1, then another trigger frame (e.g., asecond trigger frame 1415) follows the trigger frame 1410. However, ifthe cascaded subfield is set to 0, then no trigger frame will follow thetrigger frame 1410 within the same TWT service period.

A non-AP STA that receives the trigger frame 1410 has several options.The STA may transmit an uplink frame as a response to the trigger frame1410 that is intended for the STA (e.g., STAs 1, 2, 3, 4). If thecascaded field is set to 1 and the trigger frame 1410 is not intendedfor the STA, then the STA (e.g., STAs 5, 6, 7) may remain awake toreceive the second trigger frame 1415, for example (though STAs may goto sleep for the duration of the UL PPDUs transmitted as a response tothe current trigger frame). In another aspect, the STA may enter a sleepmode (or doze state) if the trigger frame 1410 was not intended for theSTA and the cascaded field of the trigger frame 1410 was set to 0. Afterreceiving the uplink transmissions from the various STAs, the AP maytransmit an acknowledgment (e.g., a multi-block acknowledgment (MBA)).In another aspect, a STA may start contending independently to accessthe medium after the frame exchange enabled by a trigger frame with acascaded field equal to 0. In certain embodiments, the STA should notstart contending to access the medium after receiving a trigger framethat contains a cascaded field equal to 1.

FIG. 15 is an exemplary diagram of a TWT group assignment field 1500within a TWT element for a broadcast TWT for multiple STAs. Referring toFIG. 15, the TWT group ID subfield may have 7 bits (e.g., correspondingto B0 to B6), the zero offset present subfield may have 1 bit (e.g.,corresponding to B7), the zero offset of group subfield may have 48 or 0bits (e.g., corresponding to B8 to B55), the TWT unit subfield may have4 bits (e.g., corresponding to B56 to B59), and the TWT offset subfieldmay have 12 bits (e.g., corresponding to B60 to B71). Within the TWToffset subfield, there may be a start AID subfield, an end AID subfield,and a reserved subfield. The start AID subfield may have 5 bits, the endAID subfield may have 5 bits, and the reserve subfield may have 2 bits.Although FIG. 15 depicts start AID and end AID subfields, other IDsassigned by an AP aside from AIDs may also be used.

The TWT group assignment field may be negotiated and used by an AP toallocate TWTs for STAs within a group. For each STA in the groupidentified by the TWT group ID, the TWT group assignment subfield mayprovide information for staggered (offset) TWTs within the group itself.In an aspect, the TWT group assignment subfield may be used when the APwants to stagger UL single user transmissions from multiple STAs of agroup. In another aspect, the TWT group assignment subfield may be usedto specify the group of STAs to wake up at a TWT. For example, the TWTgroup assignment field may identify the range of STAs that are scheduledto wake up at the specified TWT.

In an aspect, when the trigger field within the request type field isset to 1, the TWT group ID may specify the 7 most significant bits ofthe AID (or another AP assigned ID) of each of the STAs that belong tothe group that is to wake up at a certain TWT. The TWT unit may bereserved, for example, to indicate an offset of uplink transmissionsfrom the first TWT is not needed since uplink transmissions may betrigger after an XIFS, in which the XIFS may be a short interframe space(SIFS) or a point coordination function (PCF) interframe space (PIFS)).The TWT offset field may contain the 5 least significant bits of thestart AID and the 5 least significant bits of the end AID of the group.

In another aspect, when the zero offset present is set to 1, the zerooffset of group field may specify the TWT if the TWT wake time field isnot present. In another aspect, for the basic broadcast TWT case, theTIM element may also provide a list of STAs to be polled by triggers. Inan aspect, a broadcast TWT that supports multiple STAs may improvesignaling for purposes of identifying a group of STAs for multi-useroperation in a TWT element.

FIG. 16 illustrates an exemplary diagram of a second TWT element format1600. Referring to FIG. 16, a TWT element 1605 may include an element IDfield (e.g., 1 octet in length), a length field (e.g., 1 octet inlength), a control field (e.g., 1 octet in length), a request type field(e.g., 2 octets in length), a target wake time field (e.g., 2, 4, 6, or8 octets in length), a TWT group assignment field (optional), a nominalminimum wake duration field (e.g., 1 octet in length), a TWT wakeinterval mantissa field (e.g., 2 octet in length), a TWT channel(optional), and/or an NDP paging field (optional as well). The one ormore of the request type field, target wake time field, TWT groupassignment field, nominal minimum wake duration field, TWT wake intervalmantissa field, and/or TWT channel field may make up a TWT set orequivalently TWT parameter set. The TWT element 1605 may have one ormore TWT parameter sets, which may be used to indicate different TWTservice period(s).

The control field may have multiple subfields, such as a NDP pagingindicator subfield (e.g., 1 bit), a broadcast subfield (e.g., 1 bit), aresponder PM (passive mode) mode subfield (e.g., 1 bit), and/or areserved subfield (e.g., 5 bits). The broadcast bit may be used toindicate whether the TWT element 1605 is a broadcast TWT, in whichtarget wake times may not be negotiated between an AP and a STA, orwhether the TWT element 1605 is a solicited TWT, in which target waketimes may be negotiated between an AP and a STA or between a STA andanother STA. For example, when the broadcast bit is set to 1, then theTWT element 1605 may be a broadcast TWT, and when the broadcast bit isset to 0, then the TWT element 1605 may be a solicited TWT. Thebroadcast bit may also be referred to as a non-negotiable indication. Inone configuration, the responder PM mode subfield may indicate that aTWT responder may be in a doze state outside of the TWT SPs (e.g., for abroadcast TWT, the TWT responder may be the AP). In one option, the APmay set the responder PM mode subfield to 1 to indicate that the AP maybe in a doze state outside of the TWT SPs. Alternatively, the AP may setthe responder PM mode subfield to 0 if the AP is not allowed to enterinto a power save mode. In another configuration, the AP may indicatethat the AP is in power save mode by transmitting one or more triggerframes, which may include resource allocations (e.g., resource units)not allocated to any STAs during a TWT service period during which theAP intends to enter power save mode.

The length field may indicate the length of the TWT element 1605 and maybe used to determine the number of TWT parameter sets within the TWTelement 1605. For example, if the length field indicates that the TWTelement 1605 is 8 bytes, then the TWT element 1605 may have one TWTparameter set (e.g., 7 bytes of fields for the one set and one byte ofControl field). If the length field indicates 15 bytes, then the TWTelement 1605 may have two TWT parameter sets. As such, the length fieldmay indicate the number of TWT sets.

The request type field may have one or more of the following subfields,such as a repetition subfield, a trigger subfield, a reserved subfield,a flow type subfield, a TWT flow identifier subfield, a wake intervalexponent subfield, and/or a TWT protection subfield. In an aspect, therequest type field may be 1 byte in length and include a repetitionsubfield (e.g., 2 bits), a trigger subfield (e.g., 1 bit), a TWT flowidentifier subfield (e.g., 3 bits), and a wake interval exponent (e.g.,2 bits). In another aspect, the request type field may not include thewake interval exponent subfield, whose value may be preconfigured withina device (e.g., a device may have a preconfigured value of 10 withrespect to the wake interval exponent field). If the TWT is periodic(e.g., the TWT set may contain a non-zero value of the TWT wake intervalmantissa field), then the repetition subfield may indicate the number ofvalid TWT service periods associated with the TWT minus 1 specified bythe TWT parameter set. The “minus 1” accounts for the TWT indicated inthe target wake time field. For example, if the TWT is valid for 6 TWTservice periods, then the repetition field may be set to 5. In anaspect, if the TWT wake interval mantissa subfield is set to 0, then theTWT is not periodic. By contrast, if the TWT interval mantissa subfieldhas a non-zero value, then the TWT may be periodic and may repeat for asmany times as specified by the value indicated in the repetitionsubfield. The TWT Wake Interval may be determined based on a product ofthe TWT wake interval mantissa and 2 elevated to the power of the valueindicated in the wake interval exponent (period=TWT Wake IntervalMantissa×2^(Wake Interval Exponent)) In another aspect, a repetitionsubfield set to 0 may indicate an aperiodic TWT.

The trigger subfield indicates whether a trigger (e.g., a trigger frame)will be sent at the start of a target wake time(s) specified by the TWTset. In such embodiment this field may be set to 1. Otherwise it may beset to 0 to indicate that there will be no trigger frame sent at thestart of the target wake time(s). The TWT flow identifier subfieldindicates the type of data flow expected during the TWT serviceperiod(s) specified by the TWT set. The TWT flow identifier subfield maybe associated with values indicated in FIG. 12. The target wake timesubfield may include the 2 least significant bytes of the value that theTSF timer (as contained in the timestamp field of a beacon frametransmitted in that instant of time) will have at the first (ifperiodic) or only TWT (if aperiodic). In another aspect, the target waketime subfield may include a shifted subset of the 2 least significantbytes of the TSF timer. For example, assuming the TSF timer has 8 bytes,instead of including the least significant 2 bytes, the subset may beshifted in which the TWT field includes the second and third leastsignificant bytes of the 8 byte representation of the TSF timer, inwhich case the time resolution may not be of say 1 microsecond, butrather 256 microseconds. By doing so the 2 byte TWT field may indicatelarger time values (while losing some resolution). In certainembodiments, the bit shifting may occur at the bit level rather than thebyte level.

The TWT protection subfield may indicate that the TWT service period(s)specified by a corresponding TWT parameter set may be protected or not(or asked to be protected or not in a TWT request). In one aspect, whenthe TWT protection subfield is set to 0, then the TWT service period(s)may not be protected. In another aspect, when the TWT protectionsubfield is set to 1, the subfield may indicate that STAs associatedwith the AP sending the TWT element 1605 and that have read the framecarrying the TWT element 1605 should not contend to access the mediumfor the specified duration of the TWT service period(s) indicated in thecorresponding TWT set. In another embodiment, only STAs that havetraffic that is allowed by the AP to be delivered during the TWT serviceperiod(s) may contend to access the medium. For example, when the APsends a TWT element that indicates that there is no trigger frame at thestart of the TWT, and the TWT is an announced TWT (e.g., STAs shouldsend a frame to the AP), then only the STAs that may have certain typeof traffic (e.g., PS-Polls or U-APSD trigger frames) may access themedium to transmit their frames. In another aspect, when the TWTprotection subfield is set to 1, the subfield may indicate that STAsthat are not associated with the AP and that have read the framecarrying the TWT element 1605 should not contend to access the mediumfor the specified durations of the TWT service period(s). The AP thatset the TWT protection subfield to 1 may also indicate that the APintends to transmit NAV setting frames at the start of the TWT serviceperiod(s) to protect at least a part of the duration of the TWT serviceperiod(s). If the TWT element 1605 contains a list of STAs for which theTWT element 1605 is intended, the intended STA recipients of the TWTelement 1605 may discard the NAV setting frame sent by the AP at thestart of the TWT service period(s) and access the medium, or transmit toany frame that is sent by the AP immediately (e.g., in SIFS time). Inanother aspect, the AP that set the TWT protection subfield to 1 mayindicate that scheduled data exchanges during the TWT SP may be precededby a multi-user (MU) request to send (RTS) and clear to send (CTS)message exchange.

In an aspect, another AP that has set up another BSS and is within rangeof the AP that sent the TWT element 1605 (e.g., is able to read theframe carrying the TWT element 1605) may not allocate resources to anyof the STAs associated with the another AP during the TWT serviceperiod(s) so as to minimize the risk of inter-BSS collisions.

In the foregoing description, unless expressly indicated, methods,functions, protocols, and techniques described with respect to a STA mayalso be applicable to an AP, and vice versa.

FIG. 17 shows an example functional block diagram of a wireless device1702 that may perform TWT scheduling within the wireless communicationsystem 100 of FIG. 1. The wireless device 1702 is an example of a devicethat may be configured to implement the various methods describedherein. For example, the wireless device 1702 may comprise one of theAPs 104, 302, 602, 902 or one of the STAs 112, 114, 116, 118, 306, 308,310, 606, 608, 610, 906, 908, 910.

The wireless device 1702 may include a processor 1704 which controlsoperation of the wireless device 1702. The processor 1704 may also bereferred to as a central processing unit (CPU). Memory 1706, which mayinclude both read-only memory (ROM) and random access memory (RAM), mayprovide instructions and data to the processor 1704. A portion of thememory 1706 may also include non-volatile random access memory (NVRAM).The processor 1704 typically performs logical and arithmetic operationsbased on program instructions stored within the memory 1706. Theinstructions in the memory 1706 may be executable (by the processor1704, for example) to implement the methods described herein.

The processor 1704 may comprise or be a component of a processing systemimplemented with one or more processors. The one or more processors maybe implemented with any combination of general-purpose microprocessors,microcontrollers, digital signal processors (DSPs), field programmablegate array (FPGAs), programmable logic devices (PLDs), controllers,state machines, gated logic, discrete hardware components, dedicatedhardware finite state machines, or any other suitable entities that canperform calculations or other manipulations of information.

The processing system may also include machine-readable media forstoring software. Software shall be construed broadly to mean any typeof instructions, whether referred to as software, firmware, middleware,microcode, hardware description language, or otherwise. Instructions mayinclude code (e.g., in source code format, binary code format,executable code format, or any other suitable format of code). Theinstructions, when executed by the one or more processors, cause theprocessing system to perform the various functions described herein.

The wireless device 1702 may also include a housing 1708, and thewireless device 1702 may include a transmitter 1710 and/or a receiver1712 to allow transmission and reception of data between the wirelessdevice 1702 and a remote device. The transmitter 1710 and the receiver1712 may be combined into a transceiver 1714. An antenna 1716 may beattached to the housing 1708 and electrically coupled to the transceiver1714. The wireless device 1702 may also include multiple transmitters,multiple receivers, multiple transceivers, and/or multiple antennas.

The wireless device 1702 may also include a signal detector 1718 thatmay be used to detect and quantify the level of signals received by thetransceiver 1714 or the receiver 1712. The signal detector 1718 maydetect such signals as total energy, energy per subcarrier per symbol,power spectral density, and other signals. The wireless device 1702 mayalso include a digital signal processor (DSP) 1720 for use in processingsignals. The DSP 1720 may be configured to generate a packet fortransmission. In some aspects, the packet may comprise a PPDU.

The wireless device 1702 may further comprise a user interface 1722 insome aspects. The user interface 1722 may comprise a keypad, amicrophone, a speaker, and/or a display. The user interface 1722 mayinclude any element or component that conveys information to a user ofthe wireless device 1702 and/or receives input from the user.

When the wireless device 1702 is implemented as a STA (e.g., the STAs306, 606, 906) or as an AP (e.g., the APs 302, 602, 902), the wirelessdevice 1702 may also comprise a TWT component 1724.

In one configuration, the wireless device 1702 may be a TWT requesterfor solicit TWTs. In this configuration, the TWT component 1724 may beconfigured to transmit a first message that includes a first triggerfield to a second wireless device (e.g., a TWT responder). The firsttrigger field may indicate whether the first message includes a requestfor a trigger message to be sent by the second wireless device at astart of a TWT service period. The TWT component 1724 may be configuredto receive a second message from the second wireless device. The secondmessage may include a second trigger field based on the first message.The second trigger field may indicate whether the second wireless devicewill transmit the trigger message at the start of the TWT serviceperiod. In an aspect, the first message may include a requested TWT, thefirst trigger field may be set to 1, and the first message may requestthe trigger message to be sent at the requested TWT. In another aspect,the second message may include a scheduled TWT, the second trigger fieldmay be set to 1, and the second message may indicate that the secondwireless device may transmit the trigger message at the scheduled TWT.In another aspect, the scheduled TWT may be different from a requestedTWT included in the first message. In one embodiment, the TWT component1724 may be configured to determine a TWT schedule based on the receivedsecond message and to determine whether to transmit to the secondwireless device based on the determined TWT schedule. In thisembodiment, the TWT component 1724 may be configured to determine theTWT schedule by determining whether the TWT schedule is an implicit TWTschedule or an explicit TWT schedule based on the received secondmessage and by determining one or more TWTs associated with the TWTschedule based on the received second message. In another embodiment,the TWT component 1724 may be configured to determine whether totransmit by determining to transmit during the TWT service period when atrigger message is received from the second wireless device or bydetermining to transmit outside of the TWT service period based on EDCAparameters associated with AC_BE or AC_BK. In another aspect, the TWTcomponent 1724 may determine to transmit during the TWT service periodbased on the received trigger message, and the transmission may notbased on EDCA contention. In another embodiment, the TWT component 1724may be configured to receive a trigger message based on the determinedTWT schedule. The trigger message may include a cascaded indicator thatindicates whether the second wireless device will transmit anothertrigger message after the trigger message in the TWT service period. Inanother embodiment, the TWT component 1724 may be configured to receivea TWT information message from the second wireless device, and the TWTinformation message may include a next TWT value. The TWT component 1724may be configured to update the TWT schedule based on the received TWTinformation message. In another embodiment, the TWT schedule may be theimplicit TWT schedule, and the TWT component 1724 may be configured totransmit a TWT information message to the second wireless device. TheTWT information message may indicate a suspension of the implicit TWTschedule or a resumption of the implicit TWT schedule after the implicitTWT schedule has been suspended. In another aspect, the first messagemay include a TWT channel indicator that indicates a channel and achannel width that the TWT component 1724 may use for communicating withthe second wireless device during the TWT service period. In anotheraspect, the first message may include an OFDMA bitmap that indicates oneor more OFDMA channels and channel widths to be used for communicatingwith the second wireless device.

In another configuration, the wireless device 1702 may be a TWTresponder for solicit TWTs. In this configuration, the TWT component1724 may be configured to receive, from a second wireless device, afirst message that includes a first trigger field. The first triggerfield may indicate whether the first message includes a request for atrigger message to be sent by the wireless device 1702 at a start of aTWT service period. The TWT component 1724 may be configured todetermine a TWT schedule based on the received first message. The TWTcomponent 1724 may be configured to transmit a second message to thesecond wireless device. The second message may include the TWT scheduleand a second trigger field based on the determined TWT schedule. Thesecond trigger field may indicate whether the wireless device 1702 maytransmit the trigger message at the start of the TWT service period. Inan aspect, the first message may include a requested TWT, the firsttrigger field may be set to 1, and the first message may request thetrigger message to be sent at the requested TWT. In another aspect, thesecond message may include a scheduled TWT, the second trigger field maybe set to 1, and the second message may indicate that the wirelessdevice 1702 will transmit the trigger message at the scheduled TWT. Inanother aspect, the scheduled TWT may be different from a requested TWTincluded in the first message. In an embodiment, the TWT component 1724may be configured to determine the TWT schedule by determining if thefirst trigger field includes the request for the trigger message and byscheduling one or more TWTs for the second wireless device if the firsttrigger field includes the request for the trigger message. In anotherembodiment, the TWT component 1724 may be configured to transmit a TWTinformation message that includes a next TWT value that is differentfrom all TWT values associated with the TWT schedule included in thesecond message. In another embodiment, the TWT schedule may be animplicit TWT schedule, and the TWT component 1724 may be configured toreceive a TWT information message from the second wireless device. TheTWT information message may indicate a suspension of the implicit TWTschedule or a resumption of the implicit TWT schedule after the implicitTWT schedule has been suspended. In another aspect, the second messagemay include a TWT channel indicator that indicates a channel and achannel width to be used for communicating between the wireless device1702 and the second wireless device during the TWT service period. Inanother embodiment, the TWT component 1724 may be configured to transmita trigger message that includes a cascaded indicator. The cascadedindicator may indicate whether the wireless device 1702 will transmitanother trigger message after the trigger message in the TWT serviceperiod. In another aspect, the second message may include a TWTprotection indicator that indicates whether message exchanged with thewireless device 1702 based on the TWT schedule are to be preceded by anRTS and a CTS message exchange.

In another configuration, the wireless device 1702 may broadcast TWTs toother wireless devices. In this configuration, the TWT component 1724may be configured to determine a TWT schedule and to broadcasting amessage that includes the TWT schedule to other wireless devices. Themessage may include a broadcast indicator that indicates the TWTschedule is a broadcast TWT schedule. In an aspect, the broadcast TWTschedule may include non-negotiable TWT parameters for communicatingbetween the wireless device 1702 and at least one wireless device of thewireless devices. In another aspect, the message may further include atrigger field that indicates whether the wireless device 1702 willtransmit a trigger message at a start of a TWT service period. Inanother aspect, the message may include a TWT flow identifier field thatindicates a type of data flow allowed during a TWT service period. Inanother aspect, the type of data flow allowed may include MU OFDMArandom access for wireless devices unassociated with the wireless device1702, MU OFDMA random access for wireless devices associated with thewireless device 1702, MU DL OFDMA scheduled access for wireless devicesindicated in a TIM, MU UL OFDMA scheduled access for wireless devicesindicated in the TIM, MU UL MIMO scheduled access for wireless devicesindicated in the TIM, MU DL MIMO scheduled access for wireless devicesindicated in the TIM. In another aspect, the TWT flow identifier fieldmay indicates one of the following types of allowed data flows: noconstraints on a type of message to be exchanged with the wirelessdevice 1702, messages containing feedback information or managementinformation can be exchanged with the wireless device 1702 and triggermessages from the wireless device 1702 do not include resource units forrandom access, messages containing feedback information or managementinformation can be exchanged with the wireless device 1702 and triggermessages from the wireless device 1702 include resource units for randomaccess, messages containing quality of service information can beexchanged with the wireless device 1702, or no traffic is expected to becommunicated to or from the wireless device 1702. In another aspect, theTWT schedule may be an implicit TWT schedule or an explicit TWTschedule. In another aspect, the TWT schedule may be an explicit TWTschedule, the TWT schedule may includes one or more TWT parameter sets,and each TWT parameter set may correspond to a scheduled TWT. In anotherembodiment, the TWT schedule may be an implicit TWT schedule, and theTWT component 1724 may be configured to transmit a TWT informationmessage to the second wireless device. The TWT information message mayindicate a suspension of the implicit TWT schedule or a resumption ofthe implicit TWT schedule after the implicit TWT schedule has beensuspended. In another embodiment, the TWT component 1724 may beconfigured to transmit a TWT information message to the second wirelessdevice, and the TWT information message may indicate a differentscheduled TWT than in the TWT schedule in the broadcasted message. Inanother embodiment, the TWT component 1724 may be configured to transmita trigger message based on the TWT schedule. The trigger message mayinclude a cascaded indicator that indicates whether the wireless device1702 will transmit additional trigger messages in the TWT serviceperiod. In another aspect, the message may include a TWT groupassignment field, and the TWT group assignment field may include a rangeof identifiers that identifies a group of wireless devices scheduled towake up at a TWT during a TWT service period. In another aspect, themessage may include a repetition indicator, and the repetition indicatormay indicate a number of TWT service periods for which a scheduled TWTindicated in the message are valid. In another aspect, the message mayinclude a TWT protection indicator that indicates whether messagesexchanged with the wireless device 1702 based on the TWT schedule are tobe preceded by an RTS and a CTS message exchange.

In another configuration, the wireless device 1702 may receive broadcastTWTs and determine whether to join the broadcast TWT. In thisconfiguration, the TWT component 1724 may be configured to receive froma second wireless device a message that includes a TWT schedule. Themessage may include a broadcast indicator that indicates the TWTschedule is a broadcast TWT schedule. The TWT component 1724 may beconfigured to determine one or more TWTs for the wireless device 1702based on the TWT schedule. In an aspect, the broadcast TWT schedule mayinclude non-negotiable TWT parameters for communicating between thewireless device 1702 and the second wireless device. In another aspect,the message may include a trigger field that indicates whether thesecond wireless device will transmit a trigger message at a start of aTWT service period. In another aspect, the message may include a TWTflow identifier field that indicates a type of data flow allowed duringa TWT service period. In another aspect, the TWT flow identifier fieldmay indicate one of the following: no constraints on a type of messageto be exchanged with the second wireless device, messages containingfeedback information or management information can be exchanged with thesecond wireless device and trigger messages from the second wirelessdevice do not include resource units for random access, messagescontaining feedback information or management information can beexchanged with the second wireless device and trigger messages from thesecond wireless device include resource units for random access,messages containing quality of service information can be exchanged withthe second wireless device, or no traffic is expected to be communicatedto or from the second wireless device. In another aspect, the TWTschedule may be an implicit TWT schedule or an explicit TWT schedule. Inanother aspect, the TWT schedule may be an explicit TWT schedule, theTWT schedule may include one or more TWT parameter sets, and each TWTparameter set may correspond to a scheduled TWT. In another aspect, theTWT schedule may be an implicit TWT schedule, and the TWT component 1724may be configured to receive a TWT information message from the secondwireless device. The TWT information message may indicate a suspensionof the implicit TWT schedule or a resumption of the implicit TWTschedule after the implicit TWT schedule has been suspended. In anotherembodiment, the TWT component 1724 may be configured to receive a TWTinformation message from the second wireless device. The TWT informationmessage may indicate a different scheduled TWT than in the receivedmessage. In another aspect, the message may include a repetitionindicator, and the repetition indicator may indicate a number of TWTservice periods for which a scheduled TWT indicated in the message arevalid. In another embodiment, the TWT component 1724 may be configuredto receive a trigger message based on the determined one or more TWTs.In another aspect, the trigger message may include a cascaded indicatorthat indicates whether the second wireless device will transmitadditional trigger messages after the trigger message in a TWT serviceperiod. In another embodiment, the TWT component 1724 may be configuredto determine to transmit to the second wireless device during a TWTservice period when the trigger message is received from the secondwireless device and to determine to transmit to the second wirelessdevice outside of the TWT service period based on EDCA parametersassociated with an AC_BE or an AC_BK.

In another configuration, the wireless device 1702 may be a TWTrequester determining whether to switch operating modes. In thisconfiguration, the TWT component 1724 may be configured to determinewhether to switch to an active mode, a power save mode, or a TWT powersave mode. During the TWT power save mode, the wireless device 1702 mayenter an awake state during TWT service periods and may enter a dozestate outside of the TWT service periods. The TWT component 1724 may beconfigured to transmit a message to a second wireless device based onthe determination. In another aspect, the TWT service periods may beidentified based on a TWT schedule associated with the wireless device1702. In another aspect, the message may include a power managementindicator that indicates a mode to which the wireless device 1702intends switch. In another embodiment, the TWT component 1724 may beconfigured to receive an indication from the second wireless deviceinstructing the wireless device 1702 to switch to or to switch away fromthe TWT power save mode. In another aspect, the indication may includean EOSP indicator set to 1. In another embodiment, the TWT component1724 may be configured to determine whether to switch by determining ifthere is additional data for transmission or reception, by receivingfrom the second wireless device a QoS message with an EOSP indicator setto 1, or by receiving from the second wireless device a trigger messagewith a cascaded indicator set to 0 in which the trigger message is notintended for the wireless device 1702. In another embodiment, the TWTcomponent 1724 may be configured to determine a mode of the secondwireless device. In another embodiment, the TWT component 1724 may beconfigured to determine the mode of the second wireless device byreceiving a second message from the second wireless device, in whichsecond message may include a responder mode indicator that indicateswhether the second wireless device is in a doze state outside of the TWTservice periods. The determination of the mode of the second wirelessdevice may be based on the responder mode indicator. In anotherembodiment, the TWT component 1724 may be configured to determine themode of the second wireless device by receiving a trigger message fromthe second wireless device. The determination of the mode of the secondwireless device may be based on whether the trigger message includesresource allocations to any wireless devices. In another embodiment, theTWT component 1724 may be configured to receive from the second wirelessdevice a second message that includes a traffic indication map, and thetraffic indication map may indicate a mode of operation for the wirelessdevice 1702 to select.

In another configuration, the wireless device 1702 may be a TWTresponder with respect to operating modes. In this configuration, theTWT component 1724 may be configured to receive a message from a secondwireless device that indicates an intention of the second wirelessdevice to switch to an operating mode that is one of an active mode, apower save mode, or a TWT power save mode. During the TWT power savemode, the second wireless device may enter an awake state during TWTservice periods and may enter a doze state outside of the TWT serviceperiods. The TWT component 1724 may be configured to store the operatingmode associated with the second wireless device and to transmit to thesecond wireless device an acknowledgment of the operating mode switch.In an aspect, the TWT service periods may be identified based on a TWTschedule associated with the second wireless device. In another aspect,the message may include a power management indicator that indicates theoperating mode to which the second wireless device intends to switch. Inanother embodiment, the TWT component 1724 may be configured to transmita QoS message that may include an EOSP indicator set to 1 to instructthe second wireless device to switch operating modes. In anotherembodiment, the TWT component 1724 may be configured to transmit aresponder mode indicator that indicates whether the wireless device 1702is in a doze state outside of the TWT service periods. In anotherembodiment, the TWT component 1724 may be configured to transmit atrigger message with unassigned resources to indicate that the wirelessdevice 1702 will enter into a doze state. In another embodiment, the TWTcomponent 1724 may be configured to transmit a traffic indication mapthat indicates the operating mode for the second wireless device toselect. In another embodiment, the TWT component 1724 may be configuredto transmit an indication to the second wireless device instructing thesecond wireless device to switch to or to switch away from the TWT powersave mode.

The various components of the wireless device 1702 may be coupledtogether by a bus system 1726. The bus system 1726 may include a databus, for example, as well as a power bus, a control signal bus, and astatus signal bus in addition to the data bus. Components of thewireless device 1702 may be coupled together or accept or provide inputsto each other using some other mechanism.

Although a number of separate components are illustrated in FIG. 17, oneor more of the components may be combined or commonly implemented. Forexample, the processor 1704 may be used to implement not only thefunctionality described above with respect to the processor 1704, butalso to implement the functionality described above with respect to thesignal detector 1718, the DSP 1720, the user interface 1722, and/or theTWT component 1724. Further, each of the components illustrated in FIG.17 may be implemented using a plurality of separate elements.

FIG. 18 is a functional block diagram of an example wirelesscommunication device 1800 that performs TWT scheduling. The wirelesscommunication device 1800 may include a receiver 1805, a processingsystem 1810, and a transmitter 1815. The processing system 1810 mayinclude a TWT component 1824 and a mode component 1826.

In one configuration, the wireless communication device 1800 may be aTWT requester for solicit TWTs. In this configuration, the processingsystem 1810, the TWT component 1824, and/or the transmitter 1815 may beconfigured to transmit a first message that includes a first triggerfield to a second wireless device (e.g., a TWT responder). The firsttrigger field may indicate whether the first message includes a requestfor a trigger message to be sent by the second wireless device at astart of a TWT service period. The processing system 1810, the TWTcomponent 1824, and/or the receiver 1805 may be configured to receive asecond message from the second wireless device. The second message mayinclude a second trigger field based on the first message. The secondtrigger field may indicate whether the second wireless device willtransmit the trigger message at the start of the TWT service period. Inan aspect, the first message may include a requested TWT, the firsttrigger field may be set to 1, and the first message may request thetrigger message to be sent at the requested TWT. In another aspect, thesecond message may include a scheduled TWT, the second trigger field maybe set to 1, and the second message may indicate that the secondwireless device may transmit the trigger message at the scheduled TWT.In another aspect, the scheduled TWT may be different from a requestedTWT included in the first message. In one embodiment, the processingsystem 1810 and/or the TWT component 1824 may be configured to determinea TWT schedule based on the received second message and to determinewhether to transmit to the second wireless device based on thedetermined TWT schedule. In this embodiment, the processing system 1810and/or the TWT component 1824 may be configured to determine the TWTschedule by determining whether the TWT schedule is an implicit TWTschedule or an explicit TWT schedule based on the received secondmessage and by determining one or more TWTs associated with the TWTschedule based on the received second message. In another embodiment,the processing system 1810 and/or the TWT component 1824 may beconfigured to determine whether to transmit by determining to transmitduring the TWT service period when a trigger message is received fromthe second wireless device or by determining to transmit outside of theTWT service period based on EDCA parameters associated with AC_BE orAC_BK. In another aspect, the processing system 1810 and/or the TWTcomponent 1824 may determine to transmit during the TWT service periodbased on the received trigger message, and the transmission may notbased on EDCA contention. In another embodiment, the processing system1810, the TWT component 1824, and/or the receiver 1805 may be configuredto receive a trigger message based on the determined TWT schedule. Thetrigger message may include a cascaded indicator that indicates whetherthe second wireless device will transmit another trigger message afterthe trigger message in the TWT service period. In another embodiment,the processing system 1810, the TWT component 1824, and/or the receiver1805 may be configured to receive a TWT information message from thesecond wireless device, and the TWT information message may include anext TWT value. The processing system 1810 and/or The TWT component 1824may be configured to update the TWT schedule based on the received TWTinformation message. In another embodiment, the TWT schedule may be theimplicit TWT schedule, and the processing system 1810, the TWT component1824, and/or the transmitter 1815 may be configured to transmit a TWTinformation message to the second wireless device. The TWT informationmessage may indicate a suspension of the implicit TWT schedule or aresumption of the implicit TWT schedule after the implicit TWT schedulehas been suspended. In another aspect, the first message may include aTWT channel indicator that indicates a channel and a channel width thatthe TWT component 1824 may use for communicating with the secondwireless device during the TWT service period. In another aspect, thefirst message may include an OFDMA bitmap that indicates one or moreOFDMA channels and channel widths to be used for communicating with thesecond wireless device.

In another configuration, the wireless communication device 1800 may bea TWT responder for solicit TWTs. In this configuration, the processingsystem 1810, the TWT component 1824, and/or the receiver 1805 may beconfigured to receive, from a second wireless device, a first messagethat includes a first trigger field. The first trigger field mayindicate whether the first message includes a request for a triggermessage to be sent by the wireless communication device 1800 at a startof a TWT service period. The processing system 1810 and/or The TWTcomponent 1824 may be configured to determine a TWT schedule based onthe received first message. The TWT component 1824, the processingsystem 1810, and/or the transmitter 1815 may be configured to transmit asecond message to the second wireless device. The second message mayinclude the TWT schedule and a second trigger field based on thedetermined TWT schedule. The second trigger field may indicate whetherthe wireless communication device 1800 may transmit the trigger messageat the start of the TWT service period. In an aspect, the first messagemay include a requested TWT, the first trigger field may be set to 1,and the first message may request the trigger message to be sent at therequested TWT. In another aspect, the second message may include ascheduled TWT, the second trigger field may be set to 1, and the secondmessage may indicate that the wireless communication device 1800 willtransmit the trigger message at the scheduled TWT. In another aspect,the scheduled TWT may be different from a requested TWT included in thefirst message. In an embodiment, the processing system 1810 and/or theTWT component 1824 may be configured to determine the TWT schedule bydetermining if the first trigger field includes the request for thetrigger message and by scheduling one or more TWTs for the secondwireless device if the first trigger field includes the request for thetrigger message. In another embodiment, the processing system 1810, theTWT component 1824, and/or the transmitter 1815 may be configured totransmit a TWT information message that includes a next TWT value thatis different from all TWT values associated with the TWT scheduleincluded in the second message. In another embodiment, the TWT schedulemay be an implicit TWT schedule, and the processing system 1810, the TWTcomponent 1824, and/or the receiver 1805 may be configured to receive aTWT information message from the second wireless device. The TWTinformation message may indicate a suspension of the implicit TWTschedule or a resumption of the implicit TWT schedule after the implicitTWT schedule has been suspended. In another aspect, the second messagemay include a TWT channel indicator that indicates a channel and achannel width to be used for communicating between the wirelesscommunication device 1800 and the second wireless device during the TWTservice period. In another embodiment, the processing system 1810, theTWT component 1824, and/or the transmitter 1815 may be configured totransmit a trigger message that includes a cascaded indicator. Thecascaded indicator may indicate whether the wireless communicationdevice 1800 will transmit another trigger message after the triggermessage in the TWT service period. In another aspect, the second messagemay include a TWT protection indicator that indicates whether messageexchanged with the wireless communication device 1800 based on the TWTschedule are to be preceded by an RTS and a CTS message exchange.

In another configuration, the wireless communication device 1800 maybroadcast TWTs to other wireless devices. In this configuration, theprocessing system 1810 and/or the TWT component 1824 may be configuredto determine a TWT schedule and to broadcast a message that includes theTWT schedule to other wireless devices. The message may include abroadcast indicator that indicates the TWT schedule is a broadcast TWTschedule. In an aspect, the broadcast TWT schedule may includenon-negotiable TWT parameters for communicating between the wirelesscommunication device 1800 and at least one wireless device of thewireless devices. In another aspect, the message may further include atrigger field that indicates whether the wireless communication device1800 will transmit a trigger message at a start of a TWT service period.In another aspect, the message may include a TWT flow identifier fieldthat indicates a type of data flow allowed during a TWT service period.In another aspect, the type of data flow allowed may include MU OFDMArandom access for wireless devices unassociated with the wirelesscommunication device 1800, MU OFDMA random access for wireless devicesassociated with the wireless communication device 1800, MU DL OFDMAscheduled access for wireless devices indicated in a TIM, MU UL OFDMAscheduled access for wireless devices indicated in the TIM, MU UL MIMOscheduled access for wireless devices indicated in the TIM, MU DL MIMOscheduled access for wireless devices indicated in the TIM. In anotheraspect, the TWT flow identifier field may indicates one of the followingtypes of allowed data flows: no constraints on a type of message to beexchanged with the wireless communication device 1800, messagescontaining feedback information or management information can beexchanged with the wireless communication device 1800 and triggermessages from the wireless communication device 1800 do not includeresource units for random access, messages containing feedbackinformation or management information can be exchanged with the wirelesscommunication device 1800 and trigger messages from the wirelesscommunication device 1800 include resource units for random access,messages containing quality of service information can be exchanged withthe wireless communication device 1800, or no traffic is expected to becommunicated to or from the wireless communication device 1800. Inanother aspect, the TWT schedule may be an implicit TWT schedule or anexplicit TWT schedule. In another aspect, the TWT schedule may be anexplicit TWT schedule, the TWT schedule may includes one or more TWTparameter sets, and each TWT parameter set may correspond to a scheduledTWT. In another embodiment, the TWT schedule may be an implicit TWTschedule, and the processing system 1810, the TWT component 1824, and/orthe transmitter 1815 may be configured to transmit a TWT informationmessage to the second wireless device. The TWT information message mayindicate a suspension of the implicit TWT schedule or a resumption ofthe implicit TWT schedule after the implicit TWT schedule has beensuspended. In another embodiment, the processing system 1810, the TWTcomponent 1824, and/or the transmitter 1815 may be configured totransmit a TWT information message to the second wireless device, andthe TWT information message may indicate a different scheduled TWT thanin the TWT schedule in the broadcasted message. In another embodiment,the processing system 1810, the TWT component 1824, and/or thetransmitter 1815 may be configured to transmit a trigger message basedon the TWT schedule. The trigger message may include a cascadedindicator that indicates whether the wireless communication device 1800will transmit additional trigger messages in the TWT service period. Inanother aspect, the message may include a TWT group assignment field,and the TWT group assignment field may include a range of identifiersthat identifies a group of wireless devices scheduled to wake up at aTWT during a TWT service period. In another aspect, the message mayinclude a repetition indicator, and the repetition indicator mayindicate a number of TWT service periods for which a scheduled TWTindicated in the message are valid. In another aspect, the message mayinclude a TWT protection indicator that indicates whether messagesexchanged with the wireless communication device 1800 based on the TWTschedule are to be preceded by an RTS and a CTS message exchange.

In another configuration, the wireless communication device 1800 mayreceive broadcast TWTs and determine whether to join the broadcast TWT.In this configuration, the processing system 1810, the TWT component1824, and/or the receiver 1805 may be configured to receive from asecond wireless device a message that includes a TWT schedule. Themessage may include a broadcast indicator that indicates the TWTschedule is a broadcast TWT schedule. The processing system 1810 and/orthe TWT component 1824 may be configured to determine one or more TWTsfor the wireless communication device 1800 based on the TWT schedule. Inan aspect, the broadcast TWT schedule may include non-negotiable TWTparameters for communicating between the wireless communication device1800 and the second wireless device. In another aspect, the message mayinclude a trigger field that indicates whether the second wirelessdevice will transmit a trigger message at a start of a TWT serviceperiod. In another aspect, the message may include a TWT flow identifierfield that indicates a type of data flow allowed during a TWT serviceperiod. In another aspect, the TWT flow identifier field may indicateone of the following: no constraints on a type of message to beexchanged with the second wireless device, messages containing feedbackinformation or management information can be exchanged with the secondwireless device and trigger messages from the second wireless device donot include resource units for random access, messages containingfeedback information or management information can be exchanged with thesecond wireless device and trigger messages from the second wirelessdevice include resource units for random access, messages containingquality of service information can be exchanged with the second wirelessdevice, or no traffic is expected to be communicated to or from thesecond wireless device. In another aspect, the TWT schedule may be animplicit TWT schedule or an explicit TWT schedule. In another aspect,the TWT schedule may be an explicit TWT schedule, the TWT schedule mayinclude one or more TWT parameter sets, and each TWT parameter set maycorrespond to a scheduled TWT. In another aspect, the TWT schedule maybe an implicit TWT schedule, and the processing system 1810, the TWTcomponent 1824, and/or the receiver 1805 may be configured to receive aTWT information message from the second wireless device. The TWTinformation message may indicate a suspension of the implicit TWTschedule or a resumption of the implicit TWT schedule after the implicitTWT schedule has been suspended. In another embodiment, the processingsystem 1810, the TWT component 1824, and/or the receiver 1805 may beconfigured to receive a TWT information message from the second wirelessdevice. The TWT information message may indicate a different scheduledTWT than in the received message. In another aspect, the message mayinclude a repetition indicator, and the repetition indicator mayindicate a number of TWT service periods for which a scheduled TWTindicated in the message are valid. In another embodiment, theprocessing system 1810, the TWT component 1824, and/or the receiver 1805may be configured to receive a trigger message based on the determinedone or more TWTs. In another aspect, the trigger message may include acascaded indicator that indicates whether the second wireless devicewill transmit additional trigger messages after the trigger message in aTWT service period. In another embodiment, the processing system 1810and/or the TWT component 1824 may be configured to determine to transmitto the second wireless device during a TWT service period when thetrigger message is received from the second wireless device and todetermine to transmit to the second wireless device outside of the TWTservice period based on EDCA parameters associated with an AC_BE or anAC_BK.

In another configuration, the wireless communication device 1800 may bea TWT requester determining whether to switch operating modes. In thisconfiguration, the processing system 1810, the mode component 1826,and/or the TWT component 1824 may be configured to determine whether toswitch to an active mode, a power save mode, or a TWT power save mode.During the TWT power save mode, the wireless communication device 1800may enter an awake state during TWT service periods and may enter a dozestate outside of the TWT service periods. The processing system 1810,the TWT component 1824, the mode component 1826, and/or the transmitter1815 may be configured to transmit a message to a second wireless devicebased on the determination. In another aspect, the TWT service periodsmay be identified based on a TWT schedule associated with the wirelesscommunication device 1800. In another aspect, the message may include apower management indicator that indicates a mode to which the wirelesscommunication device 1800 intends switch. In another embodiment, theprocessing system 1810, the TWT component 1824, the mode component 1826,and/or the receiver 1805 may be configured to receive an indication fromthe second wireless device instructing the wireless communication device1800 to switch to or to switch away from the TWT power save mode. Inanother aspect, the indication may include an EOSP indicator set to 1.In another embodiment, the processing system 1810, the TWT component1824, and/or the mode component 1826 may be configured to determinewhether to switch by determining if there is additional data fortransmission or reception, by receiving from the second wireless devicea QoS message with an EOSP indicator set to 1, or by receiving from thesecond wireless device a trigger message with a cascaded indicator setto 0 in which the trigger message is not intended for the wirelesscommunication device 1800. In another embodiment, the processing system1810, the TWT component 1824, and/or the mode component 1826 may beconfigured to determine a mode of the second wireless device. In anotherembodiment, the processing system 1810, the TWT component 1824, and/orthe mode component 1826 may be configured to determine the mode of thesecond wireless device by receiving a second message from the secondwireless device, in which second message may include a responder modeindicator that indicates whether the second wireless device is in a dozestate outside of the TWT service periods. The determination of the modeof the second wireless device may be based on the responder modeindicator. In another embodiment, the processing system 1810, the TWTcomponent 1824, and/or the mode component 1826 may be configured todetermine the mode of the second wireless device by receiving a triggermessage from the second wireless device. The determination of the modeof the second wireless device may be based on whether the triggermessage includes resource allocations to any wireless devices. Inanother embodiment, the processing system 1810, the TWT component 1824,the mode component 1826, and/or the receiver 1805 may be configured toreceive from the second wireless device a second message that includes atraffic indication map, and the traffic indication map may indicate amode of operation for the wireless communication device 1800 to select.

In another configuration, the wireless communication device 1800 may bea TWT responder with respect to operating modes. In this configuration,the processing system 1810, the TWT component 1824, the mode component1826, and/or the receiver 1805 may be configured to receive a messagefrom a second wireless device that indicates an intention of the secondwireless device to switch to an operating mode that is one of an activemode, a power save mode, or a TWT power save mode. During the TWT powersave mode, the second wireless device may enter an awake state duringTWT service periods and may enter a doze state outside of the TWTservice periods. The processing system 1810, the TWT component 1824,and/or the mode component 1826 may be configured to store the operatingmode associated with the second wireless device and to transmit to thesecond wireless device an acknowledgment of the operating mode switch.In an aspect, the TWT service periods may be identified based on a TWTschedule associated with the second wireless device. In another aspect,the message may include a power management indicator that indicates theoperating mode to which the second wireless device intends to switch. Inanother embodiment, the processing system 1810, the TWT component 1824,the mode component 1826, and/or the transmitter 1815 may be configuredto transmit a QoS message that may include an EOSP indicator set to 1 toinstruct the second wireless device to switch operating modes. Inanother embodiment, the processing system 1810, the TWT component 1824,the mode component 1826, and/or the transmitter 1815 may be configuredto transmit a responder mode indicator that indicates whether thewireless communication device 1800 is in a doze state outside of the TWTservice periods. In another embodiment, the processing system 1810, theTWT component 1824, the mode component 1826, and/or the transmitter 1815may be configured to transmit a trigger message with unassignedresources to indicate that the wireless communication device 1800 willenter into a doze state. In another embodiment, the processing system1810, the TWT component 1824, the mode component 1826, and/or thetransmitter 1815 may be configured to transmit a traffic indication mapthat indicates the operating mode for the second wireless device toselect. In another embodiment, the processing system 1810, the TWTcomponent 1824, the mode component 1826, and/or the transmitter 1815 maybe configured to transmit an indication to the second wireless deviceinstructing the second wireless device to switch to or to switch awayfrom the TWT power save mode.

The receiver 1805, the processing system 1810, the TWT component 1824,the mode component 1826, and/or the transmitter 1815 may be configuredto perform one or more functions discussed above with respect to blocks405, 410, 415, 420, 425, 430, 435, and 440 of FIG. 4; blocks 505, 510,515, 520, 525, and 530 of FIG. 5; blocks 705, 710, 715, 720, and 725 ofFIG. 7; blocks 805, 810, 815, 820, 825, 830, and 835 of FIG. 8; blocks1005, 1010, 1015, 1020, and 1025 of FIG. 10; and blocks 1105, 1110,1115, 1120, 1125, 1130, 1135, and 1140 of FIG. 11. The receiver 1805 maycorrespond to the receiver 1712. The processing system 1810 maycorrespond to the processor 1704. The transmitter 1815 may correspond tothe transmitter 1710. The TWT component 1824 may correspond to the TWTcomponent 126, the TWT component 124, and/or the TWT component 1724.

In one configuration, the wireless communication device 1800 may be aTWT requester for solicit TWTs. In this configuration, the wirelesscommunication device 1800 may include means for transmitting a firstmessage that includes a first trigger field to a second wireless device(e.g., a TWT responder). The first trigger field may indicate whetherthe first message includes a request for a trigger message to be sent bythe second wireless device at a start of a TWT service period. Thewireless communication device 1800 may include means for receiving asecond message from the second wireless device. The second message mayinclude a second trigger field based on the first message. The secondtrigger field may indicate whether the second wireless device willtransmit the trigger message at the start of the TWT service period. Inan aspect, the first message may include a requested TWT, the firsttrigger field may be set to 1, and the first message may request thetrigger message to be sent at the requested TWT. In another aspect, thesecond message may include a scheduled TWT, the second trigger field maybe set to 1, and the second message may indicate that the secondwireless device may transmit the trigger message at the scheduled TWT.In another aspect, the scheduled TWT may be different from a requestedTWT included in the first message. In one embodiment, the wirelesscommunication device 1800 may include means for determining a TWTschedule based on the received second message and means for determiningwhether to transmit to the second wireless device based on thedetermined TWT schedule. In this embodiment, the means for determiningthe TWT schedule may be configured to determine whether the TWT scheduleis an implicit TWT schedule or an explicit TWT schedule based on thereceived second message and to determine one or more TWTs associatedwith the TWT schedule based on the received second message. In anotherembodiment, the means for determining whether to transmit may beconfigured to determine to transmit during the TWT service period when atrigger message is received from the second wireless device or todetermine to transmit outside of the TWT service period based on EDCAparameters associated with AC_BE or AC_BK. In another aspect, thewireless communication device 1800 may determine to transmit during theTWT service period based on the received trigger message, and thetransmission may not based on EDCA contention. In another embodiment,the wireless communication device 1800 may include means for receiving atrigger message based on the determined TWT schedule. The triggermessage may include a cascaded indicator that indicates whether thesecond wireless device will transmit another trigger message after thetrigger message in the TWT service period. In another embodiment, thewireless communication device 1800 may include means for receiving a TWTinformation message from the second wireless device, and the TWTinformation message may include a next TWT value. The wirelesscommunication device 1800 may include means for updating the TWTschedule based on the received TWT information message. In anotherembodiment, the TWT schedule may be the implicit TWT schedule, and thewireless communication device 1800 may include means for transmitting aTWT information message to the second wireless device. The TWTinformation message may indicate a suspension of the implicit TWTschedule or a resumption of the implicit TWT schedule after the implicitTWT schedule has been suspended. In another aspect, the first messagemay include a TWT channel indicator that indicates a channel and achannel width that the wireless communication device 1800 may use forcommunicating with the second wireless device during the TWT serviceperiod. In another aspect, the first message may include an OFDMA bitmapthat indicates one or more OFDMA channels and channel widths to be usedfor communicating with the second wireless device.

In another configuration, the wireless communication device 1800 may bea TWT responder for solicit TWTs. In this configuration, the wirelesscommunication device 1800 may include means for receiving, from a secondwireless device, a first message that includes a first trigger field.The first trigger field may indicate whether the first message includesa request for a trigger message to be sent by the wireless communicationdevice 1800 at a start of a TWT service period. The wirelesscommunication device 1800 may include means for determining a TWTschedule based on the received first message. The wireless communicationdevice 1800 may include means for transmitting a second message to thesecond wireless device. The second message may include the TWT scheduleand a second trigger field based on the determined TWT schedule. Thesecond trigger field may indicate whether the wireless communicationdevice 1800 may transmit the trigger message at the start of the TWTservice period. In an aspect, the first message may include a requestedTWT, the first trigger field may be set to 1, and the first message mayrequest the trigger message to be sent at the requested TWT. In anotheraspect, the second message may include a scheduled TWT, the secondtrigger field may be set to 1, and the second message may indicate thatthe wireless communication device 1800 will transmit the trigger messageat the scheduled TWT. In another aspect, the scheduled TWT may bedifferent from a requested TWT included in the first message. In anembodiment, the means for determining the TWT schedule may be configuredto determine if the first trigger field includes the request for thetrigger message and to schedule one or more TWTs for the second wirelessdevice if the first trigger field includes the request for the triggermessage. In another embodiment, the wireless communication device 1800may include means for transmitting a TWT information message thatincludes a next TWT value that is different from all TWT valuesassociated with the TWT schedule included in the second message. Inanother embodiment, the TWT schedule may be an implicit TWT schedule,and the wireless communication device 1800 may include means forreceiving a TWT information message from the second wireless device. TheTWT information message may indicate a suspension of the implicit TWTschedule or a resumption of the implicit TWT schedule after the implicitTWT schedule has been suspended. In another aspect, the second messagemay include a TWT channel indicator that indicates a channel and achannel width to be used for communicating between the wirelesscommunication device 1800 and the second wireless device during the TWTservice period. In another embodiment, the wireless communication device1800 may include means for transmitting a trigger message that includesa cascaded indicator. The cascaded indicator may indicate whether thewireless communication device 1800 will transmit another trigger messageafter the trigger message in the TWT service period. In another aspect,the second message may include a TWT protection indicator that indicateswhether message exchanged with the wireless communication device 1800based on the TWT schedule are to be preceded by an RTS and a CTS messageexchange.

In another configuration, the wireless communication device 1800 maybroadcast TWTs to other wireless devices. In this configuration, thewireless communication device 1800 may include means for determining aTWT schedule and means for broadcasting a message that includes the TWTschedule to other wireless devices. The message may include a broadcastindicator that indicates the TWT schedule is a broadcast TWT schedule.In an aspect, the broadcast TWT schedule may include non-negotiable TWTparameters for communicating between the wireless communication device1800 and at least one wireless device of the wireless devices. Inanother aspect, the message may further include a trigger field thatindicates whether the wireless communication device 1800 will transmit atrigger message at a start of a TWT service period. In another aspect,the message may include a TWT flow identifier field that indicates atype of data flow allowed during a TWT service period. In anotheraspect, the type of data flow allowed may include MU OFDMA random accessfor wireless devices unassociated with the wireless communication device1800, MU OFDMA random access for wireless devices associated with thewireless communication device 1800, MU DL OFDMA scheduled access forwireless devices indicated in a TIM, MU UL OFDMA scheduled access forwireless devices indicated in the TIM, MU UL MIMO scheduled access forwireless devices indicated in the TIM, MU DL MIMO scheduled access forwireless devices indicated in the TIM. In another aspect, the TWT flowidentifier field may indicates one of the following types of alloweddata flows: no constraints on a type of message to be exchanged with thewireless communication device 1800, messages containing feedbackinformation or management information can be exchanged with the wirelesscommunication device 1800 and trigger messages from the wirelesscommunication device 1800 do not include resource units for randomaccess, messages containing feedback information or managementinformation can be exchanged with the wireless communication device 1800and trigger messages from the wireless communication device 1800 includeresource units for random access, messages containing quality of serviceinformation can be exchanged with the wireless communication device1800, or no traffic is expected to be communicated to or from thewireless communication device 1800. In another aspect, the TWT schedulemay be an implicit TWT schedule or an explicit TWT schedule. In anotheraspect, the TWT schedule may be an explicit TWT schedule, the TWTschedule may includes one or more TWT parameter sets, and each TWTparameter set may correspond to a scheduled TWT. In another embodiment,the TWT schedule may be an implicit TWT schedule, and the wirelesscommunication device 1800 may include means for transmitting a TWTinformation message to the second wireless device. The TWT informationmessage may indicate a suspension of the implicit TWT schedule or aresumption of the implicit TWT schedule after the implicit TWT schedulehas been suspended. In another embodiment, the wireless communicationdevice 1800 may include means for transmitting a TWT information messageto the second wireless device, and the TWT information message mayindicate a different scheduled TWT than in the TWT schedule in thebroadcasted message. In another embodiment, the wireless communicationdevice 1800 may include means for transmitting a trigger message basedon the TWT schedule. The trigger message may include a cascadedindicator that indicates whether the wireless communication device 1800will transmit additional trigger messages in the TWT service period. Inanother aspect, the message may include a TWT group assignment field,and the TWT group assignment field may include a range of identifiersthat identifies a group of wireless devices scheduled to wake up at aTWT during a TWT service period. In another aspect, the message mayinclude a repetition indicator, and the repetition indicator mayindicate a number of TWT service periods for which a scheduled TWTindicated in the message are valid. In another aspect, the message mayinclude a TWT protection indicator that indicates whether messagesexchanged with the wireless communication device 1800 based on the TWTschedule are to be preceded by an RTS and a CTS message exchange.

In another configuration, the wireless communication device 1800 mayreceive broadcast TWTs and determine whether to join the broadcast TWT.In this configuration, the wireless communication device 1800 mayinclude means for receiving from a second wireless device a message thatincludes a TWT schedule. The message may include a broadcast indicatorthat indicates the TWT schedule is a broadcast TWT schedule. Thewireless communication device 1800 may include means for determining oneor more TWTs for the wireless communication device 1800 based on the TWTschedule. In an aspect, the broadcast TWT schedule may includenon-negotiable TWT parameters for communicating between the wirelesscommunication device 1800 and the second wireless device. In anotheraspect, the message may include a trigger field that indicates whetherthe second wireless device will transmit a trigger message at a start ofa TWT service period. In another aspect, the message may include a TWTflow identifier field that indicates a type of data flow allowed duringa TWT service period. In another aspect, the TWT flow identifier fieldmay indicate one of the following: no constraints on a type of messageto be exchanged with the second wireless device, messages containingfeedback information or management information can be exchanged with thesecond wireless device and trigger messages from the second wirelessdevice do not include resource units for random access, messagescontaining feedback information or management information can beexchanged with the second wireless device and trigger messages from thesecond wireless device include resource units for random access,messages containing quality of service information can be exchanged withthe second wireless device, or no traffic is expected to be communicatedto or from the second wireless device. In another aspect, the TWTschedule may be an implicit TWT schedule or an explicit TWT schedule. Inanother aspect, the TWT schedule may be an explicit TWT schedule, theTWT schedule may include one or more TWT parameter sets, and each TWTparameter set may correspond to a scheduled TWT. In another aspect, theTWT schedule may be an implicit TWT schedule, and the wirelesscommunication device 1800 may include means for receiving a TWTinformation message from the second wireless device. The TWT informationmessage may indicate a suspension of the implicit TWT schedule or aresumption of the implicit TWT schedule after the implicit TWT schedulehas been suspended. In another embodiment, the wireless communicationdevice 1800 may include means for receiving a TWT information messagefrom the second wireless device. The TWT information message mayindicate a different scheduled TWT than in the received message. Inanother aspect, the message may include a repetition indicator, and therepetition indicator may indicate a number of TWT service periods forwhich a scheduled TWT indicated in the message are valid. In anotherembodiment, the wireless communication device 1800 may include means forreceiving a trigger message based on the determined one or more TWTs. Inanother aspect, the trigger message may include a cascaded indicatorthat indicates whether the second wireless device will transmitadditional trigger messages after the trigger message in a TWT serviceperiod. In another embodiment, the wireless communication device 1800may include means for determining to transmit to the second wirelessdevice during a TWT service period when the trigger message is receivedfrom the second wireless device and means for determining to transmit tothe second wireless device outside of the TWT service period based onEDCA parameters associated with an AC_BE or an AC_BK.

In another configuration, the wireless communication device 1800 may bea TWT requester determining whether to switch operating modes. In thisconfiguration, the wireless communication device 1800 may include meansfor determining whether to switch to an active mode, a power save mode,or a TWT power save mode. During the TWT power save mode, the wirelesscommunication device 1800 may enter an awake state during TWT serviceperiods and may enter a doze state outside of the TWT service periods.The wireless communication device 1800 may include means fortransmitting a message to a second wireless device based on thedetermination. In another aspect, the TWT service periods may beidentified based on a TWT schedule associated with the wirelesscommunication device 1800. In another aspect, the message may include apower management indicator that indicates a mode to which the wirelesscommunication device 1800 intends switch. In another embodiment, thewireless communication device 1800 may include means for receiving anindication from the second wireless device instructing the wirelesscommunication device 1800 to switch to or to switch away from the TWTpower save mode. In another aspect, the indication may include an EOSPindicator set to 1. In another embodiment, the means for determiningwhether to switch may be configured to determine if there is additionaldata for transmission or reception, to receive from the second wirelessdevice a QoS message with an EOSP indicator set to 1, or to receive fromthe second wireless device a trigger message with a cascaded indicatorset to 0 in which the trigger message is not intended for the wirelesscommunication device 1800. In another embodiment, the wirelesscommunication device 1800 may include means for determining a mode ofthe second wireless device. In another embodiment, the means fordetermining the mode of the second wireless device may be configured toreceive a second message from the second wireless device, in whichsecond message may include a responder mode indicator that indicateswhether the second wireless device is in a doze state outside of the TWTservice periods. The determination of the mode of the second wirelessdevice may be based on the responder mode indicator. In anotherembodiment, the means for determining the mode of the second wirelessdevice may be configured to receive a trigger message from the secondwireless device. The determination of the mode of the second wirelessdevice may be based on whether the trigger message includes resourceallocations to any wireless devices. In another embodiment, the wirelesscommunication device 1800 may include means for receiving from thesecond wireless device a second message that includes a trafficindication map, and the traffic indication map may indicate a mode ofoperation for the wireless communication device 1800 to select.

In another configuration, the wireless communication device 1800 may bea TWT responder with respect to operating modes. In this configuration,the wireless communication device 1800 may include means for receiving amessage from a second wireless device that indicates an intention of thesecond wireless device to switch to an operating mode that is one of anactive mode, a power save mode, or a TWT power save mode. During the TWTpower save mode, the second wireless device may enter an awake stateduring TWT service periods and may enter a doze state outside of the TWTservice periods. The wireless communication device 1800 may includemeans for storing the operating mode associated with the second wirelessdevice and means for transmitting to the second wireless device anacknowledgment of the operating mode switch. In an aspect, the TWTservice periods may be identified based on a TWT schedule associatedwith the second wireless device. In another aspect, the message mayinclude a power management indicator that indicates the operating modeto which the second wireless device intends to switch. In anotherembodiment, the wireless communication device 1800 may include means fortransmitting a QoS message that may include an EOSP indicator set to 1to instruct the second wireless device to switch operating modes. Inanother embodiment, the wireless communication device 1800 may includemeans for transmitting a responder mode indicator that indicates whetherthe wireless communication device 1800 is in a doze state outside of theTWT service periods. In another embodiment, the wireless communicationdevice 1800 may include means for transmitting a trigger message withunassigned resources to indicate that the wireless communication device1800 will enter into a doze state. In another embodiment, the wirelesscommunication device 1800 may include means for transmitting a trafficindication map that indicates the operating mode for the second wirelessdevice to select. In another embodiment, the wireless communicationdevice 1800 may include means for transmitting an indication to thesecond wireless device instructing the second wireless device to switchto or to switch away from the TWT power save mode.

For example, means for transmitting may include the processing system1810, the TWT component 1824, and/or the transmitter 1815. Means forreceiving may include the processing system 1810, the TWT component1824, and/or the receiver 1805. Means for determining a TWT schedulebased on the received second message may include the processing system1810 and/or the TWT component 1824. Means for determining whether totransmit to the second wireless device based on the determined TWTschedule may include the processing system 1810 and/or the TWT component1824. Means for updating may include the processing system 1810 and/orthe TWT component 1824. Means for determining a TWT schedule based onthe received first message may include the processing system 1810 and/orthe TWT component 1824. Means for determining the TWT schedule mayinclude the processing system 1810 and/or the TWT component 1824. Meansfor broadcasting may include the processing system 1810, the TWTcomponent 1824, and/or the transmitter 1815. Means for determining oneor more TWTs may include the processing system 1810 and/or the TWTcomponent 1824. Means for determining to transmit to the second wirelessdevice during a TWT service period may include the processing system1810 and/or the TWT component 1824. Means for determining to transmit tothe second wireless device outside of the TWT service period may includethe processing system 1810 and/or the TWT component 1824. Means fordetermining whether to switch may include the processing system 1810,the mode component 1826, and/or the TWT component 1824. Means fordetermining a mode of the second wireless device may include theprocessing system 1810, the TWT component 1824, and/or the modecomponent 1826. Means for storing may include the processing system1810, the TWT component 1824, and/or the mode component 1826.

The various operations of methods described above may be performed byany suitable means capable of performing the operations, such as varioushardware and/or software component(s), circuits, and/or module(s).Generally, any operations illustrated in the Figures may be performed bycorresponding functional means capable of performing the operations.

The various illustrative logical blocks, components and circuitsdescribed in connection with the present disclosure may be implementedor performed with a general purpose processor, a DSP, an ASIC, an FPGAor other PLD, discrete gate or transistor logic, discrete hardwarecomponents or any combination thereof designed to perform the functionsdescribed herein. A general purpose processor may be a microprocessor,but in the alternative, the processor may be any commercially availableprocessor, controller, microcontroller or state machine. A processor mayalso be implemented as a combination of computing devices, e.g., acombination of a DSP and a microprocessor, a plurality ofmicroprocessors, one or more microprocessors in conjunction with a DSPcore, or any other such configuration.

In one or more aspects, the functions described may be implemented inhardware, software, firmware, or any combination thereof. If implementedin software, the functions may be stored on or transmitted over as oneor more instructions or code on a computer-readable medium.Computer-readable media includes both computer storage media andcommunication media including any medium that facilitates transfer of acomputer program from one place to another. A storage media may be anyavailable media that can be accessed by a computer. By way of example,and not limitation, such computer-readable media can comprise RAM, ROM,EEPROM, compact disc (CD) ROM (CD-ROM) or other optical disk storage,magnetic disk storage or other magnetic storage devices, or any othermedium that can be used to carry or store desired program code in theform of instructions or data structures and that can be accessed by acomputer. Also, any connection is properly termed a computer-readablemedium. For example, if the software is transmitted from a web site,server, or other remote source using a coaxial cable, fiber optic cable,twisted pair, digital subscriber line (DSL), or wireless technologiessuch as infrared, radio, and microwave, then the coaxial cable, fiberoptic cable, twisted pair, DSL, or wireless technologies such asinfrared, radio, and microwave are included in the definition of medium.Disk and disc, as used herein, includes CD, laser disc, optical disc,digital versatile disc (DVD), floppy disk and Blu-ray disc where disksusually reproduce data magnetically, while discs reproduce dataoptically with lasers. Thus, computer readable medium comprises anon-transitory computer readable medium (e.g., tangible media).

The methods disclosed herein comprise one or more steps or actions forachieving the described method. The method steps and/or actions may beinterchanged with one another without departing from the scope of theclaims. In other words, unless a specific order of steps or actions isspecified, the order and/or use of specific steps and/or actions may bemodified without departing from the scope of the claims.

Thus, certain aspects may comprise a computer program product forperforming the operations presented herein. For example, such a computerprogram product may comprise a computer readable medium havinginstructions stored (and/or encoded) thereon, the instructions beingexecutable by one or more processors to perform the operations describedherein. For certain aspects, the computer program product may includepackaging material.

Further, it should be appreciated that components and/or otherappropriate means for performing the methods and techniques describedherein can be downloaded and/or otherwise obtained by a user terminaland/or base station as applicable. For example, such a device can becoupled to a server to facilitate the transfer of means for performingthe methods described herein. Alternatively, various methods describedherein can be provided via storage means (e.g., RAM, ROM, a physicalstorage medium such as a CD or floppy disk, etc.), such that a userterminal and/or base station can obtain the various methods uponcoupling or providing the storage means to the device. Moreover, anyother suitable technique for providing the methods and techniquesdescribed herein to a device can be utilized.

It is to be understood that the claims are not limited to the preciseconfiguration and components illustrated above. Various modifications,changes and variations may be made in the arrangement, operation anddetails of the methods and apparatus described above without departingfrom the scope of the claims.

While the foregoing is directed to aspects of the present disclosure,other and further aspects of the disclosure may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects. Thus, the claims are not intended to be limited to theaspects shown herein, but is to be accorded the full scope consistentwith the language claims, wherein reference to an element in thesingular is not intended to mean “one and only one” unless specificallyso stated, but rather “one or more.” Unless specifically statedotherwise, the term “some” refers to one or more. All structural andfunctional equivalents to the elements of the various aspects describedthroughout this disclosure that are known or later come to be known tothose of ordinary skill in the art are expressly incorporated herein byreference and are intended to be encompassed by the claims. Moreover,nothing disclosed herein is intended to be dedicated to the publicregardless of whether such disclosure is explicitly recited in theclaims. No claim element is to be construed under the provisions of 35U.S.C. §112(f), unless the element is expressly recited using the phrase“means for” or, in the case of a method claim, the element is recitedusing the phrase “step for.”

What is claimed is:
 1. A method of wireless communication by a firstwireless device, comprising: receiving a message from a second wirelessdevice that indicates an intention of the second wireless device toswitch to an operating mode that is one of an active mode, a power savemode, or a target wake time (TWT) power save mode, wherein, during theTWT power save mode, the second wireless device enters an awake stateduring TWT service periods and enters a doze state outside of the TWTservice periods; and transmitting to the second wireless device anacknowledgment of the operating mode switch.
 2. The method of claim 1,wherein the TWT service periods are identified based on a TWT scheduleassociated with the second wireless device.
 3. The method of claim 1,wherein the message includes a power management indicator that indicatesthe operating mode to which the second wireless device intends toswitch.
 4. The method of claim 1, further comprising transmitting aquality of service (QoS) message that includes an end of service period(EOSP) indicator set to 1 to instruct the second wireless device toswitch operating modes.
 5. The method of claim 1, further comprisingtransmitting a responder mode indicator that indicates whether the firstwireless device is in a doze state outside of the TWT service periods.6. The method of claim 1, further comprising transmitting a triggermessage with unassigned resources to indicate that the first wirelessdevice will enter into a doze state.
 7. The method of claim 1, furthercomprising transmitting a traffic indication map that indicates theoperating mode for the second wireless device to select.
 8. The methodof claim 1, further comprising transmitting an indication to the secondwireless device instructing the second wireless device to switch to orto switch away from the TWT power save mode.
 9. The method of claim 1,further comprising storing the operating mode associated with the secondwireless device.
 10. An apparatus for wireless communication, theapparatus being a first wireless device, comprising: means for receivinga message from a second wireless device that indicates an intention ofthe second wireless device to switch to an operating mode that is one ofan active mode, a power save mode, or a target wake time (TWT) powersave mode, wherein, during the TWT power save mode, the second wirelessdevice enters an awake state during TWT service periods and enters adoze state outside of the TWT service periods; and means fortransmitting to the second wireless device an acknowledgment of theoperating mode switch.
 11. The apparatus of claim 10, wherein the TWTservice periods are identified based on a TWT schedule associated withthe second wireless device.
 12. The apparatus of claim 10, wherein themessage includes a power management indicator that indicates theoperating mode to which the second wireless device intends to switch.13. The apparatus of claim 10, further comprising means for transmittinga quality of service (QoS) message that includes an end of serviceperiod (EOSP) indicator set to 1 to instruct the second wireless deviceto switch operating modes.
 14. The apparatus of claim 10, furthercomprising means for transmitting a responder mode indicator thatindicates whether the first wireless device is in a doze state outsideof the TWT service periods.
 15. The apparatus of claim 10, furthercomprising means for transmitting a trigger message with unassignedresources to indicate that the first wireless device will enter into adoze state.
 16. The apparatus of claim 10, further comprising means fortransmitting a traffic indication map that indicates the operating modefor the second wireless device to select.
 17. The apparatus of claim 10,further comprising means for transmitting an indication to the secondwireless device instructing the second wireless device to switch to orto switch away from the TWT power save mode.
 18. The apparatus of claim10, further comprising means for storing the operating mode associatedwith the second wireless device.
 19. An apparatus for wirelesscommunication, the apparatus being a first wireless device, comprising:a memory; and at least one processor coupled to the memory andconfigured to: receive a message from a second wireless device thatindicates an intention of the second wireless device to switch to anoperating mode that is one of an active mode, a power save mode, or atarget wake time (TWT) power save mode, wherein, during the TWT powersave mode, the second wireless device enters an awake state during TWTservice periods and enters a doze state outside of the TWT serviceperiods; and transmit to the second wireless device an acknowledgment ofthe operating mode switch.
 20. The apparatus of claim 19, wherein theTWT service periods are identified based on a TWT schedule associatedwith the second wireless device.
 21. The apparatus of claim 19, whereinthe message includes a power management indicator that indicates theoperating mode to which the second wireless device intends to switch.22. The apparatus of claim 19, wherein the at least one processor isfurther configured to transmit a quality of service (QoS) message thatincludes an end of service period (EOSP) indicator set to 1 to instructthe second wireless device to switch operating modes.
 23. The apparatusof claim 19, wherein the at least one processor is further configured totransmit a responder mode indicator that indicates whether the firstwireless device is in a doze state outside of the TWT service periods.24. The apparatus of claim 19, wherein the at least one processor isfurther configured to transmit a trigger message with unassignedresources to indicate that the first wireless device will enter into adoze state.
 25. The apparatus of claim 19, wherein the at least oneprocessor is further configured to transmit a traffic indication mapthat indicates the operating mode for the second wireless device toselect.
 26. The apparatus of claim 19, wherein the at least oneprocessor is further configured to transmit an indication to the secondwireless device instructing the second wireless device to switch to orto switch away from the TWT power save mode.
 27. The apparatus of claim19, wherein the at least one processor is further configured to storethe operating mode associated with the second wireless device.
 28. Acomputer-readable medium of a first wireless device, thecomputer-readable medium having instructions stored thereon that, whenexecuted, cause the first wireless device to: receive a message from asecond wireless device that indicates an intention of the secondwireless device to switch to an operating mode that is one of an activemode, a power save mode, or a target wake time (TWT) power save mode,wherein, during the TWT power save mode, the second wireless deviceenters an awake state during TWT service periods and enters a doze stateoutside of the TWT service periods; and transmit to the second wirelessdevice an acknowledgment of the operating mode switch.
 29. Thecomputer-readable medium of claim 28, further comprising instructionsstored thereon that, when executed, cause the first wireless device tostore the operating mode associated with the second wireless device.